Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session N70: Quantum Sensing Fundamentals |
Hide Abstracts |
Sponsoring Units: DQI Chair: Lev Krayzman, Princeton University Room: Room 409 |
Wednesday, March 8, 2023 11:30AM - 11:42AM |
N70.00001: Fundamental limits to quantum metrology with noncommuting generators James Gardner, Tuvia Gefen, Yanbei Chen Precision metrology across many applications, e.g. gravitational-wave detection, has reached or is fast approaching the quantum limit. In the quantum regime, the fundamental limit on parameter estimation is set by the information-theoretic Quantum Cramer-Rao Bound, e.g. the Energetic Quantum Limit/Mizuno Theorem for gravitational-wave interferometers. Although this limit can be saturated in single-variable cases, for multiple and continuous parameter estimation it is missed by up to a factor of a square-root of two in the signal-to-noise ratio if the probe observables (the generators of the unitary transformation) do not commute. This is the case for detuned gravitational-wave interferometers where the amplitude quadrature of the intra-cavity light does not auto-commute at different times. In this work, we explore how the missing factor can be restored and the sensitivity improved. We also consider the effects of losses. |
Wednesday, March 8, 2023 11:42AM - 11:54AM |
N70.00002: Quantum metrology beyond the asymptotic regime Sumeet Khatri, Johannes J Meyer, Jens Eisert, Philippe Faist, Daniel S França In quantum metrology, one of the major applications of quantum technologies, the ultimate precision limits with which an unknown parameter encoded in a quantum state can be estimated is often stated in terms of the Cramer-Rao bound. Yet, the Cramer-Rao bound implicitly assumes that sufficiently many independent and identically distributed copies of the state are available to estimate the expectation value of a suitable observable that serves as an estimator. The operational relevance of the Cramer-Rao bound can be cast in doubt in regimes in which this expectation value depends significantly on events that happen with vanishing probability, and when only a limited number of samples are available. In this work, we consider the fundamental limits on estimation when only a finite number of copies of the state are available. Our approach is to formulate the task of parameter estimation analogously to the task of multiple hypothesis testing, thereby opening up the extensively-developed toolbox of hypothesis testing for use in the realm of quantum metrology. We start by defining a single-shot, operational definition of a measure of sensitivity, which is formulated as a semi-definite program, and derive bounds relating it to well-known one-shot entropy measures. We then give an upper bound on the asymptotic decay rate of the error in terms of Chernoff divergences. Finally, when restricted to the case of a pure state evolving under a fixed Hamiltonian, we find explicit formulas for the success probability and characterize the optimal probe states. This perspective on quantum metrology opens up a plethora of new directions of research into the non-asymptotic setting of quantum metrology. |
Wednesday, March 8, 2023 11:54AM - 12:06PM |
N70.00003: Achieving Heisenberg-limited sensitivity with scrambling dynamics Bryce H Kobrin, Thomas Schuster, Brad Mitchell, Maxwell Block, Norman Y Yao Quantum-enhanced metrology leverages entanglement to improve sensitivity to an external signal. It is often assumed that achieving beyond-classical sensitivities requires preparing finely tuned entangled states, such as the GHZ state or a spin-squeezed state. Here, we demonstrate instead that the fundamental limit on quantum sensing -- the celebrated Heisenberg limit -- can be achieved with a much broader class of entangled states, and we introduce an explicit protocol for preparing such states and reading out an accumulated phase. Crucially, our protocol requires only the ability to evolve forward and backward in time under generic interacting quantum dynamics and is thus compatible with a wide variety of analog quantum simulators; alternatively, it can be employed in the context of digital quantum devices to suppress the effects of coherent errors. We analyze the sensitivity of our protocol for time-evolution corresponding to (i) Haar-random unitary evolution, (ii) one-dimensional spin chains and (iii) a trapped-ion quantum computer subject to control errors. Our protocol provides a witness for many-body entanglement and thus significantly relaxes the requirements for demonstrating large-scale entanglement on near-term quantum devices. |
Wednesday, March 8, 2023 12:06PM - 12:18PM |
N70.00004: Inference-based quantum sensing Cinthia Huerta Alderete, Max Hunter Gordon, Frédéric Sauvage, Akira Sone, Andrew T Sornborger, Patrick J Coles, Marco Cerezo
|
Wednesday, March 8, 2023 12:18PM - 12:30PM |
N70.00005: Quantum Advantage in Continuous Variable Sensing Jasmine Sinanan-Singh, Yuan Liu, Gabriel Mintzer, Isaac L Chuang Quantum systems of infinite-dimension such as bosonic oscillators provide vast resources for quantum sensing. Yet, a general theory on how to manipulate such bosonic modes for sensing is unknown. We present such a framework for algorithmic quantum sensing at the fundamental limits of quantum mechanics, i.e. the Heisenberg sensing limit. We manipulate the bosonic system by performing arbitrary polynomial transformations on the bosonic phase space using quantum signal processing (QSP) in a qubit+oscillator system. For continuous variable parameter estimation, we generalize Ramsey-like sensing sequences and our protocol achieves a sensitivity scaling with the Heisenberg limit, as is the case in state-of-the-art phase and displacement sensing. Furthermore, we use our bosonic QSP sensing framework to make binary decisions about signals affecting the oscillator. The sensing accuracy of a single shot qubit measurement can outperform the Heisenberg scaling as one bit of information may encode our yes/no question without violating any physical laws. We expect our algorithmic quantum sensing protocol to unify different approaches for optimal sensing and offer a new way of sensing with various applications in chemistry and physics. |
Wednesday, March 8, 2023 12:30PM - 12:42PM |
N70.00006: Quantum enhancement in magnetic field precision in partially accessible quantum many-body systems by a periodic driving Utkarsh Mishra, Abolfazl Bayat The criticality of the ground state of many-body systems is a potential resource for quantum-enhanced sensing, namely the Heisenberg precision limit. This enhancement depends on the accessibility of the whole system. We demonstrate that for partial accessibility, the data gathered by measuring a block of spins in the ground state reduces the sensing capability to the sub-Heisenberg limit. To compensate for this, we propose a driving protocol consisting of measurement on local steady-state for quantum sensing. Remarkably, the steady-state sensing shows a significant enhancement in precision compared to the ground state and even achieves super-Heisenberg scaling for low frequencies. We use this method and infer the magnetic field with the Heisenberg scaling. The origin of this precision enhancement is related to the closing of the Floquet quasienergy gap. It is in close correspondence with the vanishing of the energy gap at criticality for ground state sensing with global accessibility. The proposal is general to all the integrable models and can be implemented on existing quantum devices. |
Wednesday, March 8, 2023 12:42PM - 12:54PM |
N70.00007: Optimal time for sensing in open quantum systems zain H Saleem, Anil Shaji, Stephen K Gray We study the time-dependent quantum Fisher Information (QFI) in a simple open quantum system satisfying the Gorini-Kossakowski-Sudarshan-Lindblad master equation and |
Wednesday, March 8, 2023 12:54PM - 1:06PM |
N70.00008: Post-selected quantum metrology in noisy settings Flavio Salvati, David R Arvidsson-Shukur, Crispin H Barnes, Joe H Jenne Post-selected quantum metrology allows detectors to operate at lower intensities without reducing the input rate of quantum information. Until now, the effect of noise on such metrology has not been investigated. In my talk I will prove that post-selection can always increase the (Fisher) information per output state, even in the presence of strong depolarising noise. The extent of the possible information compression depends on the strength of the noise. I present analytical formulae pinning down this relation. My derivation holds in the case of multi-parameter quantum metrology and post-selection by a general filter (i.e., POVM). Finally, I design the optimal filter to use in noisy post-selected quantum metrology. |
Wednesday, March 8, 2023 1:06PM - 1:18PM |
N70.00009: Tensor Network Simulations of Variational Bayesian Quantum Metrology under Correlated Noise Tyler Thurtell, Akimasa Miyake Variational Bayesian metrology has emerged as a promising avenue toward quantum advantage in sensing in the presence of complex noise and prior information. For the sake of practical advantage, it is important to understand how effective parametrized protocols are as well as how robust they are to the effects of complex noise, such as spatially correlated noise. First, we propose a new family of parametrized encoding and decoding protocols, called arbitrary-axis twist ansatzes, and demonstrate that this family of ansatzes can perform better than previous ansatzes despite having fewer entangling one-axis twist operators. Second, we utilize a polynomial-size tensor network algorithm to analyze realistic variational metrology beyond the symmetric subspace of the collective spin degree of freedom. |
Wednesday, March 8, 2023 1:18PM - 1:30PM |
N70.00010: Preprocessing quantum states for noisy measurements in quantum metrology Sisi Zhou, Tuvia Gefen Quantum Fisher information (QFI) characterizes the amount of information a quantum state carries about an unknown parameter, assuming arbitrary quantum measurements can be applied on the quantum state. However, in practice, quantum measurements are usually noisy and cannot attain the QFI of a given quantum state. Here we study the metrological protocol where quantum states can be preprocessed using quantum controls before noisy measurements. We formulate the problem of identifying the optimal quantum channels to be applied on a quantum state that maximize the classical Fisher information (FI) of the noisy measurement statistics as a biconvex optimization by introducing the concept of error observables. Based on this formulation, for pure states, we prove unitary channels are optimal and also derive analytical solutions to the optimal controls in a few practically relevant cases. For classically mixed states (i.e., states of which the unknown parameter is encoded in the eigenvalues) with commuting measurement operators, we prove that coarse graining channels are optimal and provide a counter example where unitary controls are not optimal. For general quantum states and measurements, we provide useful upper and lower bounds on the FI optimized over preprocessing controls. Finally, we consider quantum states in a multi-partite system with local noisy measurements acting independently on each subsystem and prove that in the asymptotic limit, the QFI is attainable using global optimal controls for a generic class of quantum states. |
Wednesday, March 8, 2023 1:30PM - 1:42PM |
N70.00011: A path to combining squeezing and quantum non-demolition techniques to improve the prospects for the gravitational direct detection of dark matter Sohitri Ghosh, Matthew A Feldman, Seongjin Hong, Claire E Marvinney, Raphael Pooser, Jacob M Taylor Optomechanical systems have enabled a variety of novel sensors that transduce a force to a quantum-limited signal. Recent advances in these sensing technologies have led to the suggestion that heavy dark matter candidates around the Planck mass range could be detected solely through their gravitational interaction. The Windchime collaboration is developing the necessary techniques, systems, and experimental apparatus using arrays of optomechanical sensors that operate in the regime of high-bandwidth force detection, i.e., impulse metrology. Today's state-of-the-art sensors can be limited by the added noise due to the act of measurement itself. Techniques to go beyond this limit include both squeezing of the light used for measurement and incorporating backaction evading measurement by estimating quantum non-demolition operators — typically the momentum of a mechanical resonator well above its resonance frequency. Here we explore the theoretical limits to noise reduction while combining these two quantum enhanced readout techniques for these optomechanical sensors. We find that backaction evasion via velocity sensing not only works with squeezing, but it also dramatically reduces the technical challenges of using squeezed light for broadband force detection, paving the way for combining two different quantum noise reduction techniques in the context of impulse metrology. |
Wednesday, March 8, 2023 1:42PM - 1:54PM |
N70.00012: Fast iterative, adaptive frequency sensing scheme of a two-level system (theory) Avishek Chowdhury In this work we propose an iterative, adaptive sensing protocol based on Ramsey interferometry of a two-level system. Our scheme allows one to estimate unknown frequencies with a high precision from short, finite signals. It avoids several issues related to processing of decaying signals and reduces the experimental overhead related to sampling. The scheme takes advantage of the so-called Magnus based corrections to speed up and achieve high fidelity preparation of the ideal sensing state. Additionally, it utilizes several signal processing techniques to get rid of spectral leakage and scalloping losses which hinder correct frequency estimation significantly. Combining these two techniques with an iterative procedure based on enhancing the Ramsey sequence, systematic errors are mitigated while estimating frequencies from Fourier transforms. IAS compares favorably to methods that allow one to extend the coherence time of the system, e.g., CPMG, as it allows one to determine with high accuracy the frequency on a much shorter time scale. |
Wednesday, March 8, 2023 1:54PM - 2:06PM |
N70.00013: Fast iterative, adaptive frequency sensing scheme of a two-level system (experiment) Anh Tuan Le We experimentally implement the iterative adaptive sensing (IAS) protocol to precisely determine the frequency splitting of a high Q nanomechanical two-mode system. The system under investigation consists of the strongly coupled fundamental flexural in-plane and out-of-plane mode of a nano string resonator. The application of coherent control pulses to the classical two-mode system relies on dielectric frequency tuning. Tuned on resonance, the two modes coherently exchange energy, orders of magnitude faster than the decay time, allowing us to investigate the system dynamics in time-resolved measurements. To this end, we perform the IAS protocol for short signals. The protocol is based on the application of the Magnus-based strategy to the coherent control pulses of the two-level system to overcome experimental constraints such as the bandwidth limitation in pulse generation and mitigates leakage in the sensing and readout state preparation of the Ramsey protocol. In strong agreement with the theoretical prediction, the experimental results show high accuracy in frequency estimate associated to the splitting of the modes. Comparison with the traditional Ramsey protocol reveals that precise results can be obtained on much shorter time scales using IAS. |
Wednesday, March 8, 2023 2:06PM - 2:18PM |
N70.00014: An approach to direct velocity estimation using magnetomechanics Brittany R Richman, Sohitri Ghosh, Daniel Carney, Christopher J Lobb, Jacob M Taylor Today's mechanical sensors are capable of detecting extremely weak external perturbations while operating near the fundamental limits of quantum noise. However, further improvements can be made in both sensitivity and bandwidth if we can reduce the noise originating from the process of measurement itself --- the quantum mechanical backaction of measurement. One of the ways to eliminate this noise is by measuring a quantum non-demolition variable such as momentum in a free-particle system. Here we propose and characterize a theoretical model for direct velocity measurement that utilizes a magnetic-based approach. By exploiting fundamental electromagnetic principles, we demonstrate how a traditional voice-coil configuration provides a convenient detector design by generating a momentum-momentum coupling as well as a signal voltage directly proportional to velocity. Given the very small voltage signals anticipated and the need to transition from the low frequencies of this detector scheme to the much higher frequencies associated with microwave readout, we consider the coupling of the voice-coil to a voltage-sensitive superconducting circuit, namely, the well-studied Cooper-pair box (CPB). We then explore the general analytical set-up, sensitivity, and feasibility of this collective system for the purposes of achieving extremely sensitive direct-velocity measurements of a magnetic detection mass. |
Wednesday, March 8, 2023 2:18PM - 2:30PM |
N70.00015: Resonant tunneling enhanced weak value amplification for solid-state quantum metrology Bhaskaran Muralidharan, Amal Mathew, Mahadevan Subramanian Quantum metrology employing weak-value amplification can effectuate parameter estimation with an ultra-high sensitivity and has been typically experimented across quantum optics setups. Modifying an ealier proposal for the spintronic Larmor clock [1], we propose an experiemntally viable solid-state spintronic platform to realize this paradigm. The setup estimates a very weak localized Zeeman field using highly sensitive resonant energy channels. The obtained signal offers high sensitivity even in the presence of dephasing effects endemic to solid state setups, indicating experimental viability. Using the quantum Fisher information (QFI) we establish that resonant tunneling energy channels are nearly optimal for the setup and have a QFI $10^4$ times that that of other channels capable of full transmission. These results demonstrate possibilities in harnessing the inherent sensitivity of resonant tunneling for quantum metrology in solid-state devices. Given the recent advancements in quantum materials, our setup can find uses in detection of valley Zeeman effects and Rashba coupling. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700