This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

Floquet engineering offers a compelling approach for designing the time evolution of periodically driven systems. We implement a periodic atom-light coupling to realize Floquet atom optics on the strontium 1S0 – 3P1 transition. These atom optics reach pulse efficiencies above 99.4% over a wide range of frequency offsets between light and atomic resonance, even under strong driving where this detuning is on the order of the Rabi frequency. Moreover, we use Floquet atom optics to compensate for differential Doppler shifts in large momentum transfer atom interferometers and achieve state-of-the-art momentum separation in excess of 400 ℏk. This technique can be applied to any two-level system at arbitrary coupling strength, with broad application in coherent quantum control.

This conference presentation was prepared for SPIE Quantum West, 2023.

We are developing an atom interferometer that measures horizontal accelerations to form a component of a quantum inertial measurement unit. Benefitting from the inherent stability of atom interferometry, this points to a navigation system that offers long-term accuracy without recourse to GPS. To aid compactness and transportability, the sub-components of the quantum sensor are mounted in a 19-inch rack. This includes an optical system of two titanium-sapphire lasers that delivers all of the optical pulses required to operate a highly sensitive atom interferometer using 87Rb atoms. Active compensation systems that allow operation of the quantum sensor in the noisy environment of a moving vehicle are described. Finally, we give an account of recent field trials on a variety of test platforms.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

Ultracold molecules are a powerful platform for metrology, precision measurements and searches for new, beyond-the-Standard-Model physics. Sr2, thanks to its simple structure, insensitivity to external fields and narrow optical transitions, provides an excellent testbed for the search for new interactions. Here, we present a detailed characterization of our 88Sr2 molecular clock for a vibrational transition spanning the entire depth of the ground state potential. We also discuss prospects to use strontium isotopologues to place improved constraints on new mass-dependent forces, including possible pathways toward the production of ultracold 86Sr2 and 84Sr2 dimers and spectroscopy of clock lines in these species for use in the search for new mass-dependent forces.

Several clock states in Yb+, especially those within the metastable F7/2 manifold, are unusually sensitive to anticipated effects of non-Standard-Model physics. For instance, pronounced clock shifts are predicted due to Lorentz asymmetry, variations of the fine structure constant, or coupling to dark matter. Here we propose a duplex Yb+ quantum sensor dedicated to precision tests of fundamental physics. Basic design aspects are discussed and put into the context of other approaches.

The remarkable precision of optical atomic clocks offers sensitivity to new and exotic physics through tests of relativity, searches for dark matter, gravitational wave detection, and probes for beyond Standard Model particles. We have recently realized a “multiplexed” strontium optical lattice clock consisting of two or more clocks in one vacuum chamber. In this talk I will explain the motivation, concept, and operating principles of our multiplexed optical lattice clock. I will then present recent experimental results in which we performed a novel, blinded, precision test of the gravitational redshift with an array of 5 evenly-spaced atomic ensembles spanning a total height difference of 1 cm. I will present the error budget produced from our systematic evaluation, and the recently unblinded results of our first test.Finally, I will discuss the outlook for future searches for new physics with our apparatus, including a novel direct test of the Einstein Equivalence Principle.

Optical clocks are the apotheosis of precision measurement, but they require frequent maintenance by scientists. The supporting laser systems are a particularly demanding component of these instruments. To reduce complexity and increase robustness we propose an optical clock with trapped alkali-like ions that use the S_1/2 → D_3/2 electric quadrupole transition. Compared to traditional group-II ion clocks this reduces the number of laser wavelengths required, and uses hyperfine state preparation and readout techniques enabled by the nuclear spin I = 1/2. We consider ²²⁵Ra⁺ as a candidate system for a clock with three electronic states, and discuss the potential to help realize a transportable optical clock.

Quantum sensing devices such as atomic clocks enable unmatched precision in various area of metrology. Initially bulky laboratory devices, it is of great interest to miniaturize them to lower their energy consumption and deploy them in many embedded and mobile systems. To allow a dramatic cost reduction and miniaturization, CSEM developed and tested with success miniature atomic clocks based on wafer-level processes. On top of the control electronics and the atomic vapor cells, the optical design, the optical components and their assembly have been fully redesigned to be wafer-level fabricated. To achieve low aspect ratio and integrated optical management, thin glass planar waveguides have been implemented allowing to transport and beam shape the interrogating beam going from and to the atomic vapor gas cell. This proved a much simpler wafer scale assembly process, a monolithic construction less prone to single component alignment issues and provide much more compact atomic clocks

NASA Engineering and Safety Center has convened an independent external panel, comprising of Quantum Sensing Experts from Government, DoD, academia, and Federally funded Research and Development Center to conduct an independent technical assessment of the agency's capabilities in Quantum Sensing to understand NASA's internal needs and competencies related to Quantum Sensing and compare agency capabilities with those available externally including industry, academia, and other government agencies. The outcomes of the assessment will help the agency in establishing appropriate strategies and investments to develop and maintain the state-of-the-art sensing competence and capabilities required to meet the agency’s future needs.

Photon-number-resolved (PNR) detection of large numbers of photons in a room-temperature device is a long-standing goal for optical metrology and a variety of quantum-optics applications (e.g. heralding). The recent development of room-temperature CMOS-based imaging sensors with read noise below 1 photoelectron [1] has underscored the utility of electron counting techniques for photon-number-resolved detection. We have conducted preliminary modelling for a semiconductor-based photon-number resolving detection system and find that our models are compatible with the development of a detection system with high detection efficiency and accurate electron-number discrimination even for large (>> 10) photoelectrons.

Our initial design is to implement an optical absorption region with a metrologically useful area (e.g. > 10 µm diameter) and, similar to prior designs [1], use charge pumping techniques to collect the photogenerated carriers on a small node that serves as the gate of a readout transistor. We will consider both single-electron transistors at low temperature, as well as small-feature MOSFETs. Of critical importance is the capacitance of the readout gate, which in prior work was approximately 400 aF and supported root-mean-squared read noise between 0.1 and 0.2 electrons. Based on our prior work in surface-gated single-electron transistors we estimate that the total capacitance at the readout implemented with surface gates can be 40 aF, which would afford a factor of 10 increase in electron sensitivity. In addition, by integrating the detector with other standard single-electron (SE) device functionality such as a SE pump, we hope to perform fundamental tests of the quantum efficiency and metrology of the detector.

To date, we have mostly focused on simulations, to obtain time response and voltage ranges, along with total capacitance values. We may also report on initial electrical measurements, time permitting.

References [1] J. Ma, S. Masoodian, D.A. Starkey, E.R. Fossum, “Photon-number-resolving megapixel image sensor at room temperature without avalanche gain,” Optica 4, 12, 1474-1481 (2017).

Determining the modal structure of quantum light is important for photonic information processing, sensing, and imaging. A full modal characterization requires determining both the amplitude and phase of light’s spatial and spectral distributions, as well as its polarization. We propose using Hanbury Brown and Twiss “intensity interferometry” with a classical reference field to perform this full characterization without the need for phase stability or nonlinearities. The technique can be applied to any quantum signal, such as single photons and entangled photon pairs.

We use SPAD array technology to study carrier dynamics and spectroscopy, and particularly those of multiply excited states in semiconductor quantum dots at room temperature and at the single particle level. This helps to reveal new information inaccessible via either ensemble spectroscopy or conventional single-particle measurements.

This conference presentation was prepared for SPIE Quantum West, 2023.

Nitrogen Vacancy (NV) centers in diamond have emerged over the past few years as well-controlled quantum systems, with promising applications ranging from quantum information science to magnetic sensing. In this talk, I will describe new techniques for NV sensing – quantifying radical concentration and high-bandwidth compressed sensing. First, I will present our diamond magnetic microscope, enabling high-sensitivity and high-resolution magnetic sensing. I will demonstrate a novel technique we developed to characterize radical concentrations through their effect on the NVs (in collaboration with Uri Banin’s group). Then I will present a technique based on spectral compressed sensing, allowing high-bandwidth and large dynamic range magnetic sensing using NVs. We demonstrate the advantages of this approach and extend common compressed sensing schemes to practically “infinite resolution” in the frequency domain, further enhancing the the capabilities of our scheme.

Diamond and phosphor nanoparticles can probe biological processes on the nanoscale, sometimes with the potential for quantum-enhanced sensing. However, there are issues that must be addressed to enable widespread application. For example, in the case of magnetic sensing it is desirable to have as many nitrogen-vacancy (NV) color center as possible. Yet leftover nitrogen atoms are a source of spin noise that rapidly degrades magnetic sensitivity. In the case of phosphor nanoparticles, the ubiquitous biofluorescence background can be suppressed by upconversion in rare earth doped crystals, even for excitation laser intensities comparable to single-photon transitions. However these optical transitions have a relatively low quantum efficiency per ion. In this talk I will discuss new approaches toward solving these problems by combining both technologies, for example, heterogeneous core-shell structures involving both diamond and phosphor nanoparticles.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

The nature of dark energy is the most compelling of all outstanding problems in physical science. Although various theories for dark energy have been proposed, experimental verification or exclusion of these theories has been faced with tremendous challenges not only at cosmic scales, but also at laboratory scales. In this work, we use a levitated force sensor to detect the fifth force predicted by the chameleon theory, one of the most compelling theories for dark energy. With no signatures of the fifth force detected, we decisively rule out, for the first time, the basic chameleon model as a candidate for dark energy.

Axions and axion-like particles may couple to nuclear spins like a weak oscillating effective magnetic field, the “axion wind.” Existing proposals for detecting the axion wind sourced by dark matter exploit analogies to nuclear magnetic resonance (NMR) and aim to detect the small transverse field generated when the axion wind resonantly tips the precessing spins in a polarized sample of material. We describe a new proposal using the homogeneous precession domain (HPD) of superfluid 3He as the detection medium, where the effect of the axion wind is a small shift in the precession frequency of a large-amplitude NMR signal. We argue that this setup can provide broadband detection of multiple axion masses simultaneously, and has competitive sensitivity to other axion wind experiments such as CASPEr-Wind at masses below 1e-7 eV by exploiting precision frequency metrology in the readout stage.

This conference presentation was prepared for SPIE Quantum West, 2023.

Developments over the last decade have pushed the search for particle dark matter (DM) to new frontiers, including the keV-scale lower mass limit for thermally-produced DM. Galactic DM at this mass is kinematically matched with the energy needed to break a Cooper pair (~meV), making quantum sensors ideally-suited for DM detection applications. At Fermilab, we are constructing QUIET, a dedicated, underground quantum sensor test facility, which will be used as part of the Quantum Science Center to deploy quantum detectors in a low-background environment. I will discuss the current state of the field as well as plans to leverage this facility for DM detection down to the lower mass limit for thermal production in the early universe.

I discuss the time reversal of nonlinear many-body Hamiltonians and its application to the fields of quantum metrology and quantum information science. I present the experimental realization of such a protocol in an optically engineered many-body spin Hamiltonian. We used time-reversed Hamiltonian approach to achieve metrological gains well beyond the limit of the readout scheme. Moreover, with the same protocol, we experimentally elucidate the intimate relation between quantum information scrambling, out-of-time-order correlators, and metrological gain. In particular, I will highlight the robustness of time reversal protocols, and how these render many fast-scrambling and complex Hamiltonians useful for quantum-enhanced metrology.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

It is now well appreciated that quantum physics can be used to build better sensors. Such sensors can be based on unitary systems [1,2] like interferometers or open systems based on scattering and lossy transmission channels [3-5]. The framework of the quantum Fisher information enables one to obtain best estimates of the parameters and then one can design possible experiments that can reach Cramer- Rao bounds. I would bring out not only the importance of the quantum states used as probes, but also the importance of the ‘quantum’ measurement schemes especially the ones that depend on time reversed arrangements. I would illustrate the great usefulness of squeezed states of matter and light for metrology. [1] S. C. Burd et al., Quantum amplification of mechanical oscillator motion, Science 364, 1163 (2019). [2] G. S. Agarwal, and L. Davidovich, Quantifying quantum-amplified metrology via Fisher information, Phys. Rev. Res. 4, L 012014 (2022). [3] J. Wang, L. Davidovich, and G. S. Agarwal, Quantum sensing of open systems: Estimation of damping constants and temperature, Phys. Rev. Res. 2, 033389 (2020). [4] F. Li, T. Li, M. O. Scully, and G. S. Agarwal, Quantum advantage with seeded squeezed light for absorption measurement, Phys. Rev. Applied 15, 044030 (2021). [5] T.Li, F. Li, X. Liu, V. Yakovlev and G. S. Agarwal, Quantum-enhanced stimulated Brillouin scattering spectroscopy and imaging, OPTICA 9, 959 (2022).

Ensembles of neutral atoms enable state-of-the-art measurements of time, acceleration, and electromagnetic fields. Introducing entanglement among the constituent atoms offers a route to enhancing the precision of these measurements. One proposed approach to generating the requisite entanglement relies on the off-resonant optical coupling of one ground state to a highly excited electronic state. This technique, known as Rydberg dressing, enables local and dynamical control of interactions between neutral atoms. In this talk, I will present the engineering of Rydberg-dressed interactions by single-photon coupling to nP states in a cesium atomic clock. I will also present the creation of a squeezed spin state by local interactions that achieves a factor of 0.78(4) reduction in phase variance below the standard quantum limit.

Extreme sensitivity in measuring minute changes of phase is traditionally achieved by marvels of technology, such as a high finesse (10^6) Fabry-Perot interferometer, probed with lasers of only 1 Hz linewidth, and complex electronics. We will show that the same result can be obtained with standard unstabilized lasers emitting dual frequency combs. The source of combs has a coherence time in the microsecond range, yet a mutual coherence time between the combs of 100 s is achieved.

Quantum Langevin noise makes the observation of quantum-optical parity-time (PT) symmetry in an open system with both gain and loss elusive. Here, we challenge this problem by exploiting twin beams produced from a nonlinear parametric process, one undergoing phase-sensitive linear quantum amplification (PSA) and the other engaging balanced loss merely. Unlike previous studies involving phase-insensitive linear quantum amplification (PIA), our PSA-loss scheme enables only one pair of quadratures to evolve PT-symmetrically with variances transiting from periodic oscillations to exponential growths when crossing an exceptional point (EP), while tailors the conjugate pair with PT-adjusted quadrature squeezing. We further investigate such asymmetric PT-quadrature squeezing for quantum sensing by evaluating the quantum Cramer–Rao bound with distinct features beyond existing protocols. The proposed quadrature PT sheds new light on continuous-variable based quantum information and technology.

Nitrogen vacancy (NV) centers in diamond are atom-scale defects with long spin coherence times that can be used to sense magnetic fields with high sensitivity and spatial resolution. Typically, the magnetic field projection at a single point is measured by averaging many sequential measurements with a single NV center, or the magnetic field distribution is reconstructed by taking a spatial average over an ensemble of many NV centers, discarding information. Here we propose and implement a new sensing modality, whereby two or more NV centers are measured simultaneously, and we extract temporal and spatial correlations in their signals that would otherwise be inaccessible. We analytically derive the measurable two-point correlator, and show that optimizing the readout noise is critical for measuring correlations. We experimentally demonstrate that independent control of two NV centers can be used to measure the temporal structure of correlations.

We propose and demonstrate chip-scale based all-optical remote magnetic sensing. Specifically, we remotely interrogate mm-scale micromachined vapor cells and measure the ambient magnetic field with at a standoff distance of ~10 meters and a sensitivity of ~1 pT/√Hz. Simultaneously we are able to measure the distance between the micro-cell and the interrogating system by means of time-of-flight measurements, thus correlating between position and magnetic field. Consequently, we provide a novel toolset to remotely map arbitrary, remote and hard to access magnetic field in an unshielded environment with high sensitivity and spatial resolution.

This conference presentation was prepared for SPIE Quantum West, 2023.

Quantum interferometers are able to improve the sensitivity of classical interferometers beyond the shot-noise limit. This is done by employing squeezed states of light and destructive interference of the noise in the system. We developed a quantum SU(1,1) interferometer in the time domain. Our nonlinear quantum interferometer creates interference of the input signals at different times and frequencies. We can control the time and frequency differences for investigating the full temporal and spectral structure of the signal. This quantum interferometer can be utilized for sensing ultrafast phase changes, quantum imaging, temporal mode encoding, and studying the temporal structure of entangled photons.

The Stern-Gerlach effect, found a century ago, has become a paradigm of quantum mechanics. Unexpectedly, until recently, there has been little evidence that the original scheme with freely propagating atoms exposed to gradients from macroscopic magnets is a fully coherent quantum process. Several theoretical studies have explained why a Stern-Gerlach interferometer is a formidable challenge. Here, we provide a detailed account of the realization of a full-loop Stern-Gerlach interferometer for single atoms and use the acquired understanding to show how this setup may be used to realize an interferometer for macroscopic objects doped with a single spin. Such a realization would open the door to a new era of fundamental probes, including the realization of previously inaccessible tests at the interface of quantum mechanics and gravity.

As the quantum revolution moves forward, there is a clear need for a set of common terms to be used in characterizing the performance of single-photon sources and detectors. A common language allows fair comparison of commercial devices and helps clarify what performance can be expected. To address this need, an effort to construct a dictionary of single-photon terms was begun at the National Institute of Standards and Technology (NIST) and including input from the quantum industry and other National Metrology Institutes. We report on the progress of this effort and seek additional input from the single-photon community.

This conference presentation was prepared for SPIE Quantum West, 2023.

We experimentally implement the separation estimation between to incoherent optical sources. Our method, relying on spatial-mode demultiplexing and intensity measurements, saturates the Cramèr-Rao bound, with a five orders of magnitude gain compared to the Rayleigh limit.

High resolution, high signal-to-noise ratio and high sensitivity have always been the goals and technical bottlenecks of detection, precision measurement and imaging. Quantum detection technology is one of the disruptive cutting-edge technologies in the world. Quantum information technology is introduced into the field of classical detection, hoping to solve the difficult technical bottleneck on the basis of classical physics. Compared with traditional detection methods, quantum detection has higher sensitivity, can receive weaker signals, requires lower transmission power, and has stronger anti-interference ability. In terms of precision measurement, the characteristics of quantum mechanics are used to make the measurement accuracy break through the classical physical limit, and then improve the measurement accuracy of the detection system. But with the development of remote sensing technology and people demand for long distance detection, we completed in the early completed close quantum detection, combined with remote sensing technology, the quantum squeezed light into the receiving system, using quantum phase-free amplification technology, make up for the low efficiency of the detector, make its imaging results close to the ideal detector. We designed a set of quantum squeezing light preparation, emission /receiving system, quantum enhancement module, quantum imaging system, balance homodyne detection system, data processing system, central control system in one of the remote quantum infrared detector, effective detection distance up to 100 meters, at the same time achieve high resolution imaging, the same environment and classical laser imaging resolution increased by 1 to2 times. In March 2000, Professor Siwen Bi conducted the exploration and research on quantum remote sensing. At the beginning of 2001, Professor Siwen Bi first put forward the concept of quantum remote sensing at home and abroad. In the past 20 years, through three stages of basic theoretical scientific experiments and key technologies, we have overcome many difficulties in theoretical research scientific experiments and key technologies ,and achieved breakthrough progress and innovative results, which have laid a key foundation for the follow-up quantum laser radar quantum remote sensing products.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

Non-Hermitian optics with parity-time (PT) or anti-parity-time (APT) symmetry with controlled gain and loss has resulted in many interesting phenomena that do not necessarily have corresponding counterparts in conservative systems. If such a system enters quantum region, the gain-loss induced unavoidable Langevin noises does not preserve the symmetry. Here, we demonstrate APT symmetric nonlinear optical four-wave mixing (FWM) without involving gain and loss, and thus no Langevin noises are induced. We show that The APT phase transition across the exceptional point is connected to the generation of two-mode light squeezing: In the APT symmetry broken regime the squeezing factor oscillates and is bounded, while in the APT symmetry region the squeezing factor increase exponentially along propagation direction. We will discuss how to implement this dramatic change of quantum squeezing for precision quantum sensing.

The presentation will cover our efforts towards the metrology of quantum networks and review the metrology tools developed in our labs at NIST for quantum component and quantum network characterization, including the characterization of single-photon sources and detectors, quantum network node synchronization and entanglement distribution augmented by quantum network management and control.

In recent years, new super resolution imaging methods based on the anti-bunching properties of photons emitted by single quantum emitters have emerged. Thus far, these methods have been extremely limited in speed as they rely on very low repetition lasers to match the speed of cameras or use high-speed photon counting at individual points scanned across the surface of the object. Here, we study the use of spatio-temporally modulated illumination light to acquire photon counts from an extended region of the object. Thus, we combine high speed photon detection with extended illumination to enhance the imaging speed of anti-bunching super resolution microscopy.

I present results of a search for new physics performed by measuring isotope shifts (IS) in Yb+ at the Vuletić group at MIT and discuss plans to perform IS spectroscopy of Ca+ with Jonathan Home's group at ETH. Isotope shifts, when measured on at least two atomic transitions can be displayed in a King plot. The presence of nonlinearities in such a plot indicates the existence of effects beyond the expected first-order standard model (SM) contributions to the IS's. We measured IS's on three narrow transitions in five isotopes of Yb+ and observe King nonlinearity with more than 40 sigma confidence. Further, we find 4-sigma evidence that there are at least two distinct physical effects contributing to the observed nonlinearity. We identify the largest effect as originating from isotope-dependent differences in the 4th-order nuclear charge moment. We discuss possible sources of the second nonlinearity and find that it likely cannot be explained by the expected next-largest SM contribution.

Quantum technologies, spanning from sensing and metrology to simulations and computing, rely upon precise and low noise laser systems. Currently, we are witnessing a paradigm shift, where laboratory-based experiments are engineered such to develop reliable operating devices. The goal of providing continuous operation is key to enable their deployment for, e.g., PNT applications or cloud-based quantum computing services. Ultra-low noise laser systems are becoming integral part of these quantum devices due to their pivotal role in the effective functioning of the physics package. In fact, the performance are fundamentally linked to the noise properties of the driving laser fields, imposing the need of a careful choice of the appropriate sources, their spectral properties, and their stabilization. Here we present some of our recent ultra-stable laser system engineered for enabling several applications, we will describe ultra-stable comb and laser systems for quantum computing using neutral Yb, Sr, Rb, or Cs atoms, electric field sensing with Rydberg Rb atoms, and portable compact comb systems to enable uninterrupted operation of optical clocks in the field. A detailed noise analysis of the systems will be presented.

Atom beams are a longstanding technology for atom-based sensors and clocks. Here, we demonstrate integration of miniature Rb atomic beam using lithographically defined components and passive pumping in a cm-scale device. The device consists of two cavities connected by a series of lithographically defined channels, and the device is fabricated from stack of Si and glass layers which are anodically bonded to form a hermetically seal. The first cavity contains a vapor of atomic Rb which feeds the channel array to produce a set of atomic beams in the second cavity. The channels also provide differential pumping between the two regions, which paired graphite and non-evaporable getters pumps background gases in the second cavity. We present spectroscopy of the atom beam and Rb vapor in the device and comment on the prospects for miniaturized atomic beam clocks.

This conference presentation was prepared for SPIE Quantum West, 2023.

We report a notch-shaped coplanar microwave waveguide antenna on a glass plate designed for on-chip detection of optically detected magnetic resonance (ODMR) of fluorescent nanodiamonds (NDs). A lithographically patterned thin wire at the center of the notch area in the coplanar waveguide realizes a millimeter-scale ODMR detection area (1.5 × 2.0 mm^2) and gigahertz-broadband characteristics with low reflection (∼8%). The ODMR signal intensity in the detection area is quantitatively predictable by numerical simulation. Using this chip device, we demonstrate a uniform ODMR signal intensity over the detection area for cells, tissue, and worms.

The 20th century has witnessed the rise of quantum mechanics and its fueled scientific and technological revolution. The humankind is now on the verge of a second quantum revolution sparked by quantum information science and engineering (QISE). Entanglement as a quintessential quantum resource lies at the heart of QISE, giving rise to a plethora of quantum-enabled or enhanced capabilities that shift the landscape of communication, sensing, and computing. This talk will focus on sensing and precision metrology enhanced by entanglement, a unique and radically new resource for information processing. I will describe our recent experimental advances in entanglement-based quantum machine learning for data classification and entangled sensor networks for precise radiofrequency and optomechanical sensing. A pathway toward large-scale quantum sensor networks and prospects for future applications underpinned by quantum-enhanced sensing will also be discussed.

This conference presentation was prepared for SPIE Quantum West, 2023.

Waves propagate diffusively through disordered media due to random scattering. Though most waves are reflected, only a tiny fraction carries information from deep inside the medium. These remitted waves are widely used for noninvasive probing from seismic interferometry to diffuse optical tomography and functional near-infrared spectroscopy. The meager signal-to-noise ratio of remitted waves eventually limits the probing depth. By tailoring spatial wavefront of a laser beam, we enhance remitted signal by an order of magnitude, and increase its sensitivity to local changes inside an opaque medium. This work illustrates the potential of coherent wavefront control for noninvasive diffuse-wave imaging applications.

Light-pulse atom interferometers are excellent probes for studying gravitational interactions in quantum systems. The characteristics of the atom optics lasers are often essential in determining the performance of an atom interferometer. Here we have built a high-power laser system that enables Stark-shift-compensated dual beam splitters. Technical details of the laser system will be discussed. The second part will focus on the observation of a gravitational Aharonov-Bohm effect. When operating the interferometer with a source mass in a nonlocal regime, we identify the non-zero action-induced phase shift, deviating from that induced by deflections, as the gravitational Aharonov-Bohm phase shift.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

Quantum mechanics is grounded on the superposition principle, which is the source both of its tremendous success and technological power, as well as of the problems in understanding it. The reason why superpositions do not propagate from the microscopic to the macroscopic world are subject to debate. Spontaneous wave function collapse models have been formulated to take into account a progressive breakdown of quantum superpositions when systems are large enough; they do so by modifying the Schrödinger dynamics, and therefore they are empirically testable. Deviations are tiny, and require precision measurements. I will review collapse models, and present the most recent experimental tests.

It is acknowledged that the sensitivity and accuracy achievable by atom-interferometric quantum sensors will have significantly impact many research areas. While the sensitivity of an atomic sensor scales quadratically to the interrogation time, making spaceborne quantum sensors particularly interesting, the measurement noise is limited by the quantum projection noise. The state of the art ultracold atom source for microgravity features 1E6 Rb atoms via Bose-Einstein Condensation (BEC). In this talk, we will present a feasibility study towards 1E8 Cs atoms below 1 nK for space applications. While Cs BEC is very challenging to generate, the choice of Cs versus Rb will be briefly discussed, in the scenario of quantum gravity gradiometer for mass change studies of Earth. Instead of BEC, direct laser cooling techniques are identified as an alternative and viable approach for high flux cold atom source. We will review laser cooling techniques and the identified path forward.

Here, we describe progress toward realization of a vector magnetometer based on all-optical excitation of an atomic ensemble in a vapor cell under the conditions of electromagnetically induced transparency (EIT). The EIT resonance amplitudes depend on relative orientations of the three key vectors: laser wave-vector, polarization, and the direction of the magnetic field. By analyzing possible two-photon transitions and their combinations, we can, in principle, analytically calculate the amplitude of various EIT resonances as functions of the relative angles between the magnetic field, polarization and laser propagation vectors. By locking the polarization to one of these maxima, one can determine the plane formed by the magnetic field and the light wave vector to the accuracy better than 0.001 rad. Analysis of the relative resonance amplitude may be used to extract the full information about the magnetic field direction.

Axions and axion-like particles are well motivated candidates for dark matter and have a signature two photon vertex. The most sensitive axion dark matter search is at the gigahertz regime, which relies on microwave cavities with high quality factors resonantly converting axion dark matter to cavity photons in the background of a static magnetic field. However, axion dark matter mass could span a vast range above or below gigahertz. We describe a new proposal using integrated/on-chip photonic systems to search for axion dark matter at the optical frequency. This enables the use of waveguides to collect signal photons, which improves the detection efficiency, as well as the use of single photon, micron-sized detector, such as a charge-coupled device (CCD), which has a dark count as low as 1e−9 per pixel per second. Furthermore, due to the small scale of the experiment, a static magnetic field as large as 40 Tesla can be employed. Our setup also provides a broadband detection in terms of axion masses and has sensitivities to axion photon couplings expected for QCD axion with a mass of around 1eV.

Quantum cascade detectors (QCD) are photovoltaic mid-infrared detectors based on intersubband transitions. The sub-picosecond carrier transport between subbands and the absence of a bias voltage make QCDs ideally suited for high-speed and room temperature operation. Interband cascade detectors (ICDs) combine interband optical transitions with fast intraband transport to achieve high-frequency and broad-wavelength operation at room temperature. We report the design, fabrication, and characterization of QCDs optimized for large electrical bandwidth. Femtosecond pulses generated by a mid-infrared optical parametric oscillator are used to demonstrate QCDs with a 3-dB bandwidth of more than 20 GHz and measure the saturation characteristics of ICDs.

This conference presentation was prepared for SPIE Quantum West, 2023.

Exceptional points in parity-time symmetric optics and photonics have in recent years been promoted in various contexts of light-matter interactions. In particular, the spectrum with coalescing eigenvalues changes dramatically the photonics system's response to perturbations. The talk will discuss both some fundamental aspects of this, including limitations associated with causality, as well as some of the pros and cons for pratical sensor applications, including the noise limitations on the detection limit.

Open systems, governed by non-Hermitian Hamiltonians, evolve fundamentally differently from their Hermitian counterparts and facilitate many unusual applications. Though non-Hermitian but parity-time (PT) symmetric dynamics has been realized in various classical or semiclassical systems, its fully quantum demonstration is still lacking. Here we engineer a highly controllable anti-Hermitian spin-boson model in a circuit QED structure composed of a decaying artificial atom (pseudospin) interacting with a bosonic mode stored in a microwave resonator. Besides observing abrupt changes in the spin-boson entanglement evolution and bifurcation transition in quantum Rabi splitting, we demonstrate super-sensitive quantum sensing by mapping the observable of interest to a hitherto unobserved PT-manifested entanglement evolution. These results pave the way for exploring non-Hermitian entanglement dynamics and PT-enhanced quantum sensing empowered by nonclassical correlations.

The physics of exceptional points leads to very high sensitivity because the perturbation of an exceptionally degenerate state is highly sensitive to a system’s perturbation. This property is indeed not shared with nondegenerate systems, and it relies in the fractional power expansion (Puiseux series) describing the perturbation of eigenvalues and eigenvectors. We discuss how this property is met in systems made of coupled resonators and with coupled modes in waveguides, whose eigenvalues are the resonant frequencies and the wavenumbers, respectively. We will also discuss the experimental implementation of this principle in unstable nonlinear systems to build extremely sensitive saturated oscillators.

Whispering gallery mode resonators made from non-linear electro-optic materials are excellent platforms for frequency manipulation of electromagnetic radiation, allowing microwave up-conversion and the generation of frequency combs. By using an x-cut lithium niobate crystal to fabricate our WGM resonator, the resulting electro-optic coefficient varies around the circumference of the resonator, allowing for a simpler microwave geometry. We demonstrate a frequency comb with excellent repetition rate stability, and show results from dual combs with orthogonal polarisations. We measure the relative frequency stability of the dual combs, and find it to be 4 mHz, without any need for stabilisation or post processing.

Quantum sensing and measurement devices are reaching a new level of accuracy for high-precision measurements, allowing detection of the most minute changes in magnetic, electric, and strain fields, gravity, and time. In this talk, I will present an overview of how integrated photonic and nanophotonic devices utilize entanglement to improve measurement accuracy and sensitivity. Examples will include the development of ultrabright and ultra-efficient quantum light sources as resources for sensors, integrated photonic magnetometry with exquisite sensitivity that can be further enhanced with squeezing, and strain sensors based on optomechanical modulation of quantum emitters via surface acoustic wave resonators.

Integrated technologies represent a key enabling capability for future compact and portable atomic physics systems, including optical clocks and other sensors. In this talk, I will discuss our recent demonstration of high-fidelity detection of the state of a trapped Sr+ ion with a single-photon avalanche detector (SPAD) integrated into a microfabricated surface-electrode trap. Using an adaptive technique, we achieve ion state detection in 450 us with 99.92(1)% average fidelity. I will also discuss ongoing efforts to combine integrated detectors with integrated photonics to enable ion traps that completely eliminate the need for free-space optics for light delivery and collection.

This conference presentation was prepared for SPIE Quantum West, 2023.

Near-field scanning optical microscopy (NSOM) is a powerful technique to characterize the chemical and physical properties of materials with nanometer-scale resolution. Adaptation of NSOM has remained mainly in research labs partly due to a lack of commercial availability of high-quality probes. We present a wafer-scale realization of Campanile near-field probes. Campanile probes offer a strong local electromagnetic field enhancement, efficient far-field to near-field coupling, nanoscale spatial resolution, background-free operation, and broadband photon-plasmon coupling to enable high spatial and temporal resolution. The near-field optical mapping of dark-excitonic states of WSe2 monolayers is presented as a use-case example.

Torsion resonators loom large in the history of precision measurement; however their role in modern nanomechanics experiments is limited. In this presentation I will describe a new class of ultra-high-Q torsion nanoresonators fashioned from strained nanoribbons, and how they might be used for imaging-based quantum optomechanics experiments and chip-scale intertial sensing. Specifically, using an optical lever, we have resolved the rotation of one such nanoribbon with an imprecision 100 times smaller than the zero-point motion of its fundamental torsion mode, paving the way towards observation of radiation pressure shot noise in torque. We have also found that a strained nanoribbon can be mass-loaded without changing its torsional Q. We have used this strategy to engineer a chip-scale torsion pendulum with an ultralow damping rate of 7 micro-hertz, sufficient to resolve micro-g fluctuations of the local gravitational field.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

By combining high-resolution spectroscopy of the 3d ²D_3/2 − 3d ²D_5/2 interval with an accuracy of ∼20 Hz using direct frequency-comb Raman spectroscopy with isotope shift measurements of the 4s ²S_1/2 ↔ 3d ²D_5/2 transition in all stable even isotopes of ^ACa⁺ (A = 40, 42, 44, 46, and 48) at the accuracy of ∼1 kHz, we have been able to carry out a King plot analysis with unprecedented sensitivity to coupling between electrons and neutrons by bosons beyond the Standard Model. Furthermore, we estimate that by improved spectroscopic techniques available, King plots based on data from spectroscopy on either Ca⁺, Ba⁺ and Yb⁺ ions should be able to produce sensitivity to such potentially new bosons, which surpass other current methods in a broad mass range of 10 to 10⁸ eV/c².

Quantum correlation is the keyword in quantum information technologies. Over the last several decades, quantum correlation violating local realism has been intensively studied in various areas, but still left as a mysterious quantum phenomenon. Here, a coherence approach is applied to investigate the fundamental physics of nonlocal quantum correlation for a typical model based on entangled photon pairs without violation of quantum mechanics. As a result, a complete coherence solutions are found for coherent photons via coincidence detection, resulting in a deterministic joint basis relation between space-like separated parties in an inseparable basis-product manner.

The unique combination of atomic-scale tunability, reproducibility, and chemical specificity make molecules a paradigm-shifting category of materials for quantum information science. We imbued molecular qubits with the same read-out approach as defect-based systems, creating molecular color centers. Work on molecular color centers will be presented.

Dark energy constitutes ~70% of the universe, which explains the observed accelerated expansion of the universe. While little is known about the nature of dark energy, it is conjectured that it is a new scalar field that interacts normal matter at the cosmological scale. Recently, cold atom experiments in laboratory have contributed significantly on the constraints of chameleon and symmetron parameters. These experiments are currently limited by the knowledge of the Newtonian gravity of the test masses, and eventually by the uncertainty of the gravitational constant G. In this talk, we will present a joint project between JPL and Leibniz University Hannover, in which atom interferometers will be implemented in the 4-second microgravity environment in the Einstein-Elevator facility at Hannover, Germany. We will illustrate the measurement concept for constraining dark energy models, and report the progress of the joint effort.

Quantum mechanics allows for the realization of optimized measurements based on photon counting for the discrimination of nonorthogonal coherent states able to surpass the conventional limits of detection, such as the homodyne and heterodyne limits. Such measurements have a large potential for increasing sensitivities and information transfer in communications and for information processing. In this talk I will describe our current work in the problem of generalized measurements for coherent state discrimination. We implement an optimal inconclusive measurement for binary coherent states [1], a non-projective measurement that allows for achieving the lowest probability of error for a given rate of inconclusive results. This measurement encompasses standard measurement paradigms for state discrimination, specifically minimum error and unambiguous discrimination, and allows to transition between them in an optimal way. [1] M. T. DiMario, F. E. Becerra, Npj Quantum Inf. 8 (1), 1-8.

New particles that interact with photons, axions or dark photons, are well-motivated extensions of the standard model. I will present ways in which nonlinear quantum optics effects can be used to search for such particles. In particular, "Dark SPDC" (dSPDC) is a process in which a pump photon can down-convert to a signal photon and a dark particle idler that is not detected. The presence of a signal and its properties can be used to infer the presence of a new particle in the event. I focus on dSPDC in optical waveguides.

In this talk, I will discuss the prospects for applying quantum measurement techniques to lowering energy detection thresholds for rare-event searches to the meV scale. I will compare and contrast different methods utilizing various types of superconducting sensors, and present an overview of ongoing word to adapt qubits into meV-scale quantum sensors.

Currently, there is a critical need for localized, position-dependent calibration of quantum device response to characterize the fundamental sensing mechanism of many superconducting detectors. For example, qubit decoherence has been found to be associated with the generation of electron-hole pairs and phonons through the scattering of radiation in the qubit substrate. Novel particle physics applications seek to use these events as indicators of energy deposition, allowing quantum devices to serve as particle detectors. The low energy threshold of these proposed detectors makes them particularly well-suited for a next-generation dark matter search. We have developed a cryogenic optical beam steering system that delivers monochromatic photons in the range of 250nm - 20um across the surface of any cryogenic quantum device. In this talk, I will present the design overview and specifications of this calibration unit, along with current status and plans of the testing program.

This conference presentation was prepared for SPIE Quantum West, 2023.

Atom-light entanglement is a key concept in quantum information science. Within a Rydberg atom system, the interaction-induced dephasing is often used to produce entangled states within atomic ensembles. Here, we present a theoretical model and experimental results for the temporal evolution of an initially unentangled Rydberg spin wave into an entangled Dicke state and study effects of interference between non-classical light retrieved from the atoms and a coherent probe field. These results should be useful for a range of quantum information protocols including single photon generation and atom-light entanglement preparation.

We describe a fast imaging atomic vector magnetometer based on laser spectroscopy of the Zeeman splitting in the (6s6p) 3P1 state of Yb. In the presence of a magnetic field gradient, we observed prominent dark stripes (visible by eye or camera) in the fluorescence (556 nm) when a thermal Yb atomic beam is driven by square-wave amplitude-modulated light at RF frequencies. The 1S0-3P1 transition forms a “V” system where two laser sidebands interact simultaneously with two 3P1 Zeeman sublevels. The dark lines are contours of constant magnetic field strength, and are consistent with theoretical models dominated by Autler-Townes Splitting. The estimated magnetic field sensitivity is ≈ 10 μG (1 nT) for 100k image pixels recorded in 3 ms.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

Stimulated Brillouin scattering interactions in optical fibers involve the exchange of energy and linear momentum between the optical and acoustic fields. In most settings, the angular momenta of the two fields remain unchanged. In this presentation, I discuss the vector properties of forward stimulated Brillouin scattering processes in standard, single-mode fibers. The process make take place through guided acoustic modes of two-fold azimuthal symmetry, which appear in degenerate pairs. Analysis shows that a pair of optical pump waves, with circular and orthogonal polarizations, may stimulate a superposition the pair of acoustic modes. That superposition takes up the form of a rotating acoustic vortex beam. The stimulation process is associated with the transfer of angular momentum quanta between the optical and acoustic fields. This type of interaction adds a new dimension to stimulated Brillouin scattering processes in fibers.

We show that Doppler shifts are fundamental in gyroscopes. The implication is that it is then possible to perform frequency estimation rather than phase estimation in a passive gyroscope. By utilizing the ultra-steep gain feature of a liquid crystal light valve, we were able to show that we could beat the standard quantum limit of phase estimation by two orders of magnitude compared to a standard interferometer of the same size.

Nano- and micromechanical oscillators act as great sensors of a wide variety of signals, but their sensitivity and bandwidth can be limited by quantum backaction imposed by optomechanical displacement measurement. We experimentally demonstrate a new paradigm for optomechanical measurement and control based on strong interactions with short light pulses. Using unique nanophotonic optomechanical cavities, we show that single pulsed measurements can achieve sub-quantum-limit resolution. Moreover, we demonstrate a new protocol to deterministically produce squeezed mechanical states, which can reduce single-quadrature fluctuations to arbitrarily small magnitudes. We discuss the application of the resulting squeezing and entanglement for mechanical quantum sensing.

We present a new scheme to enhance the quantum-limited bandwidth-sensitivity product of table-top position-sensitive interferometers. It is based on a recently proposed stable optomechanical PT-symmetric sensitivity enhancement technique. We extend this technique to tabletop-scaled systems by using the membrane-in-the-middle approach. We show that the sensitivity can be enhanced in a wide frequency range by using a silicon nitride membrane as the optomechanical component. We discuss the main experimental challenges, present the results of our experimental work on a proof-of-principle room-temperature demonstration of the effect and stability, and discuss the future upgrade of our setup for a fully quantum demonstration.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

This conference presentation was prepared for SPIE Quantum West, 2023.

Quantum optics has had a profound impact on precision measurements, and recently enabled probing various physical quantities, such as magnetic fields and temperature, with nanoscale spatial resolution. In my talk, I will discuss the development and application of novel quantum metrological techniques that enable the study of biological systems in a new regime. I will start with a general introduction to quantum sensing and its applications to nanoscale nuclear magnetic resonance (NMR) spectroscopy. In this context, I will discuss how we can utilize tools from single-molecule biophysics to interface a coherent quantum sensor with individual intact biomolecules, and how this could eventually pave the way towards a new generation of biophysical and diagnostic devices. In the second part, I will discuss a theoretical proposal that utilizes variational techniques to drive a dipolar interacting spin ensemble into a metrological relevant state with Heisenberg limited sensitivity.

Flow cytometry is one of the most widespread optical methods used in the diagnosis of health disorders and disease monitoring. The ultimate goal is achieving a single biomarker sensitivity. Here we experimentally characterize the nonclassical light from the flow cytometer and observe g(2)(0) = 0.4(2). Thus, we demonstrate a single emitter sensitivity and determine that the signal due to one biomarker is at least 6 times brighter than the background noise. This result potentially enables detecting rare single biomarker occurrences with high throughput.

NIR imaging of biological samples can reveal details about the chemical makeup of the sample. To overcome the difficulties of current imaging devices, which are most sensitive in the visible region of the spectrum, we use ghost imaging with quantum entangled photons. A non-degenerate photon pair is used to probe a sample, revealing structures with fewer photons per second than starlight.

After a generic review of ODMR techniques with a NV color centers in diamonds and previous results in INRIM, I will present our results that demonstrate for the first time the possibility of making localized temperature measurements with precision under 0.1 K in neurons by exploiting ODMR techniques. When activating the firing of a neuronal network using a drug that stops the inhibitory mechanism, a significant local temperature increase is detected.

Detection and sensing of molecules via their interaction with light opens opportunities for studies ranging from nanoscale single-molecule readout to long-range experiments. Plasmonic antennas allow localized electromagnetic enhancement, allowing Raman-spectroscopic sensing with sub-nanometer spatial resolution. Further signal enhancement can be obtained through the use of molecular coherence - produced either through coherent Raman excitation or via direct infrared driving. The next level of improvements in signal-to-noise ratio will come with the use of properly engineered non-classical states of light.

Light-pulse atom interferometers (LPAIs) have demonstrated excellent sensitivity to inertial forces in laboratory settings, and significant efforts are underway to apply them in real-world environments, but maintaining high performance in a dynamic environment is challenging. With the goal of elucidating a path towards fieldable sensors, we present a multi-faceted approach based on a high data-rate grating magneto-optical trap (GMOT) LPAI, photonic-integrated-circuit (PIC) laser systems, and membrane PIC platforms for guiding atoms with evanescent-field (EF) modes.