Quantum-enhanced magnetometry by phase estimation algorithms with a single artificial atom

Abstract

Phase estimation algorithms are key protocols in quantum information processing. Besides applications in quantum computing, they can also be employed in metrology as they allow for fast extraction of information stored in the quantum state of a system. Here, we implement two suitably modified phase estimation procedures, the Kitaev-and the semiclassical Fourier-transform algorithms, using an artificial atom realized with a superconducting transmon circuit. We demonstrate that both algorithms yield a flux sensitivity exceeding the classical shot-noise limit of the device, allowing one to approach the Heisenberg limit. Our experiment paves the way for the use of superconducting qubits as metrological devices which are potentially able to outperform the best existing flux sensors with a sensitivity enhanced by few orders of magnitude.

Entanglement-based 3D magnetic gradiometry with an ultracold atomic scattering halo

“…Diverse areas in physics harness quantum correlations to improve, for example, the sensing of gravitational waves [9], time [10], and electromagnetic fields [11]. Among these applications, quantum-assisted magnetometry is an active area for a variety of platforms, including superconducting circuits [12], nuclei in molecules [13], nitrogen-vacancy centres in diamond [14], optomechanical microcavities [15], trapped ions [8], atomic vapours [11], and ultracold atoms [16,17]. Excellent wide-field measurements of magnetic fields have been investigated in nitrogen-vacancy centres in diamond [14] and ultracold atomic systems [18].…”

Comparison of non classical effects: quantum phase fluctuation, antibunching and minimum total noise in various non linear optical processes

“…To study the optical nonlinearity of nanoparticles, there is a significant body of research concerning the measurements of third order nonlinear susceptibility χ 3 which can be used as a source for the generation of third harmonic generation process [26]. With the role of quantum phase fluctuation in quantum cryptography [27], super conductivity [28,29] and with the success in experimental study of phase fluctuation [30], there has been a significant increase in importance of study of non-classical parameters.…”

Robustness of quantum-enhanced adaptive phase estimation

“…Our expression (1) differs from usual proportionality expressions in the literature, e.g., ∆φ ∝ N −℘ by explicitly recognizing the relevance of lower-order terms [4] through the use of the big-O notation [5]. QEM is vital for high-precision applications, such as gravitational wave detection [6][7][8], atomic clocks [9,10], and magnetometry [4,11] whose systems are operating at the limit of their power tolerance. Some schemes consider ideal measurements that typically involve measuring multiple particles simultaneously [12,13], whereas adaptive QEM (AQEM) focuses on single-particle measurements augmented by feedback such that the SQL is beat and the HL is approached [14][15][16].…”