Quantum-Enhanced Metrology and Sensing

Bryce Kobrin, Schuster, Thomas, Maxwell Block +4 more

We introduce a novel protocol, which enables Heisenberg-limited quantum-enhanced sensing using the dynamics of any interacting many-body Hamiltonian. Our approach - dubbed butterfly metrology - utilizes a single application of forward and reverse time evolution to produce a coherent superposition of a "scrambled" and "unscrambled" quantum state. In this way, we create metrologically-useful long-range entanglement from generic local quantum interactions. The sensitivity of butterfly metrology is given by a sum of local out-of-time-order correlators (OTOCs) - the prototypical diagnostic of quantum information scrambling. Our approach broadens the landscape of platforms capable of performing quantum-enhanced metrology; as an example, we provide detailed blueprints and numerical studies demonstrating a route to scalable quantum-enhanced sensing in ensembles of solid-state spin defects.

Jia‐Xin Peng, Baiqiang Zhu, Weiping Zhang +1 more

The detrimental impact of noise on sensing performance in quantum metrology has been widely recognized by researchers in the field. However, there are no explicit fundamental laws of physics stating that noise invariably weakens quantum metrology. We reveal that phase-covariant noise either degrades or remains neutral to sensing precision, whereas non-phase-covariant noise can potentially enhance parameter estimation, surpassing even the ultimate precision limit achievable in the absence of noise. This implies that a non-Hermitian quantum sensor may outperform its Hermitian counterpart in terms of sensing performance. To illustrate and validate our theory, we present several paradigmatic examples of magnetic field metrology.

Vittorio Giovannetti, Seth Lloyd, Lorenzo Maccone

Yi Shen, Jungeng Zhou, Jiahao Huang +1 more

We propose a quantum-enhanced metrology protocol known as partially concurrent twisting and sensing (PCTS) to effectively utilize time for high-precision sensing. In contrast to the traditional approach of separated twisting and sensing (STS), we concurrently execute twisting and sensing at the outset. Here, we explore one-axis twisting (OAT) over a short evolution period to induce spin squeezing, which has been used in several quantum-enhanced metrology. In particular for tiny estimated parameter, we analytically give the measurement precision of PCTS and demonstrate its metrological advantages compared with STS. Especially for modest particle number and OAT interaction strength, PCTS makes better use of entanglement generation time and achieves a larger metrological gain within the same total time. We estimate that our PCTS may offer up to 2 dB of metrological advantage over STS in realistic experiments with Bose condensed atoms or trapped ions. Although the measurement precision of PCTS may diminish with increasing estimated parameters, we can employ two hybrid classical-PCTS compensation techniques to facilitate high-precision measurements across a wide dynamic range. Furthermore, our approach eliminates the need to switch the estimated field, thereby reducing experimental demands and offering extensive application potential in atomic clocks and magnetometers.

Paola Cappellaro