scholarly journals Quantum-enhanced sensing of displacements and electric fields with two-dimensional trapped-ion crystals

Science ◽  
2021 ◽  
Vol 373 (6555) ◽  
pp. 673-678
Author(s):  
Kevin A. Gilmore ◽  
Matthew Affolter ◽  
Robert J. Lewis-Swan ◽  
Diego Barberena ◽  
Elena Jordan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Vibrational Mode ◽  
Center Of Mass ◽  
Trapped Ions ◽  
Quantum Limit ◽  
Many Body ◽  
Standard Quantum ◽  
Standard Quantum Limit ◽  
Atomic Systems ◽  
Electronic Spin

Fully controllable ultracold atomic systems are creating opportunities for quantum sensing, yet demonstrating a quantum advantage in useful applications by harnessing entanglement remains a challenging task. Here, we realize a many-body quantum-enhanced sensor to detect displacements and electric fields using a crystal of ~150 trapped ions. The center-of-mass vibrational mode of the crystal serves as a high-Q mechanical oscillator, and the collective electronic spin serves as the measurement device. By entangling the oscillator and collective spin and controlling the coherent dynamics via a many-body echo, a displacement is mapped into a spin rotation while avoiding quantum back-action and thermal noise. We achieve a sensitivity to displacements of 8.8 ± 0.4 decibels below the standard quantum limit and a sensitivity for measuring electric fields of 240 ± 10 nanovolts per meter in 1 second. Feasible improvements should enable the use of trapped ions in searches for dark matter.

scholarly journals Entanglement-enhanced matter-wave interferometry in a high-finesse cavity

2021 ◽  
Author(s):  
James Thompson ◽  
Graham Greve ◽  
Chengyi Luo ◽  
Baochen Wu
Keyword(s):  
Cavity Qed ◽  
Degrees Of Freedom ◽  
Inertial Sensors ◽  
Mean Field ◽  
New Physics ◽  
Matter Wave ◽  
Quantum Limit ◽  
Entangled State ◽  
Standard Quantum ◽  
Standard Quantum Limit

Abstract Entanglement is a fundamental resource that allows quantum sensors to surpass the standard quantum limit set by the quantum collapse of independent atoms. Collective cavity-QED systems have succeeded in generating large amounts of directly observed entanglement involving the internal degrees of freedom of laser-cooled atomic ensembles. Here we demonstrate cavity-QED entanglement of external degrees of freedom to realize a matter-wave interferometer of 700 atoms in which each individual atom falls freely under gravity and simultaneously traverses two paths through space while also entangled with the other atoms. We demonstrate both quantum non-demolition measurements and cavity-mediated spin interactions for generating squeezed momentum states with directly observed metrological gain 3.4^{+1.1}_{-0.9} dB and 2.5^{+0.6}_{-0.6} dB below the standard quantum limit respectively. An entangled state is for the first time successfully injected into a Mach-Zehnder light-pulse interferometer with 1.7^{+0.5}_{-0.5} dB of directly observed metrological enhancement. These results open a new path for combining particle delocalization and entanglement for inertial sensors, searches for new physics, particles, and fields, future advanced gravitational wave detectors, and accessing beyond mean-field quantum many-body physics.

scholarly journals The standard quantum limit of coherent beam combining

2019 ◽  
Vol 21 (9) ◽  
pp. 093047 ◽  
Author(s):  
C R Müller ◽  
F Sedlmeir ◽  
V O Martynov ◽  
Ch Marquardt ◽  
A V Andrianov ◽  
...  
Keyword(s):  
Coherent Beam ◽  
Quantum Limit ◽  
Standard Quantum ◽  
Standard Quantum Limit ◽  
Coherent Beam Combining ◽  
Beam Combining

scholarly journals Squeezed-light-driven force detection with an optomechanical cavity in a Mach–Zehnder interferometer

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chang-Woo Lee ◽  
Jae Hoon Lee ◽  
Hyojun Seok
Keyword(s):  
Zehnder Interferometer ◽  
Vacuum Field ◽  
Quantum Limit ◽  
Measurement Sensitivity ◽  
Force Detection ◽  
Detection Scheme ◽  
Standard Quantum ◽  
Standard Quantum Limit ◽  
Optomechanical Cavity ◽  
Mach Zehnder Interferometer

Abstract We analyze the performance of a force detector based on balanced measurements with a Mach–Zehnder interferometer incorporating a standard optomechanical cavity. The system is driven by a coherent superposition of coherent light and squeezed vacuum field, providing quantum correlation along with optical coherence in order to enhance the measurement sensitivity beyond the standard quantum limit. We analytically find the optimal measurement strength, squeezing direction, and squeezing strength at which the symmetrized power spectral density for the measurement noise is minimized below the standard quantum limit. This force detection scheme based on a balanced Mach–Zehnder interferometer provides better sensitivity compared to that based on balanced homodyne detection with a local oscillator in the low frequency regime.

scholarly journals Experimental Demonstration of a Quantum Receiver Beating the Standard Quantum Limit at Telecom Wavelength

2020 ◽  
Vol 13 (5) ◽  
Author(s):  
Shuro Izumi ◽  
Jonas S. Neergaard-Nielsen ◽  
Shigehito Miki ◽  
Hirotaka Terai ◽  
Ulrik L. Andersen
Keyword(s):  
Quantum Limit ◽  
Experimental Demonstration ◽  
Standard Quantum ◽  
Standard Quantum Limit ◽  
Telecom Wavelength
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