Quantum Phase Detection via Observable Collapse

Summary form only given.One approach to experimentally verifying that collapses occur is to nonperturbatively observe the gas and monitor N, over time. In principle, phase-contrast imaging techniques can be used to make such observations, by illuminating the cloud with a weak, far-detuned probe laser. However, because l, is relatively small, a probe that is sufficiently weak to avoid perturbing the atoms does not provide a large enough signal to accurately determine N,. This difficulty can be circumvented by sacrificing imaging resolution and measuring instead the total number of trapped atoms in the cloud. Collapses are then detected as discontinuous drops in the signal. We have implemented this detection scheme and are attempting to observe collapses and measure their frequency.Summary form only given.One approach to experimentally verifying that collapses occur is to nonperturbatively observe the gas and monitor N, over time. In principle, phase-contrast imaging techniques can be used to make such observations, by illuminating the cloud with a weak, far-detuned probe laser. However, because l, is relatively small, a probe that is sufficiently weak to avoid perturbing the atoms does not provide a large enough signal to accurately determine N,. This difficulty can be circumvented by sacrificing imaging resolution and measuring instead the total number of trapped atoms in the cloud. Collapses are then detected as discontinuous drops in the signal. We have implemented this detection scheme and are attempting to observe collapses and measure their frequency.

Conference on Lasers and Electro-OpticsNov 27, 20020 citations

Phase detection at the quantum limit

Juan F. Hodelin, Luca Pezzè, G. Khoury +2 more

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEJan 1, 20080 citations

Quantum Phase Measurement

Z. Hradil

Springer eBooksJan 1, 19951 citation

Stochastic dynamics of an electron in a Penning trap: Phase flips correlated with amplitude collapses and revivals

S. Brouard, Jesús Plata

We study the effect of noise on the axial mode of an electron in a Penning trap under parametric-resonance conditions. Our approach, based on the application of averaging techniques to the description of the dynamics, provides an understanding of the random phase flips detected in recent experiments. The observed correlation between the phase jumps and the amplitude collapses is explained. Moreover, we discuss the actual relevance of noise color to the identified phase-switching mechanism. Our approach is then generalized to analyze the persistence of the stochastic phase flips in the dynamics of a cloud of $N$ electrons. In particular, we characterize the detected scaling of the phase-jump rate with the number of electrons.We study the effect of noise on the axial mode of an electron in a Penning trap under parametric-resonance conditions. Our approach, based on the application of averaging techniques to the description of the dynamics, provides an understanding of the random phase flips detected in recent experiments. The observed correlation between the phase jumps and the amplitude collapses is explained. Moreover, we discuss the actual relevance of noise color to the identified phase-switching mechanism. Our approach is then generalized to analyze the persistence of the stochastic phase flips in the dynamics of a cloud of $N$ electrons. In particular, we characterize the detected scaling of the phase-jump rate with the number of electrons.

arXiv:1106.5390Physical Review AJun 13, 20111 citation

Observing Quantum Measurement Collapse as a Learnability Phase Transition

Utkarsh Agrawal, Javier Lopez-Piqueres, Romain Vasseur +2 more

During a quantum measurement, superpositions of states with different observable properties probabilistically collapse into one with a sharp value of the measured observable. In macroscopic quantum systems, this collapse arises via a continuous measurement-induced phase transition (MIPT) at a critical value of the strength of interaction with the measurement apparatus. MIPTs lie outside established paradigms for equilibrium or nonequilibrium critical phenomena and delineate distinct, stable dynamical and computational phases of matter. Quantum computers enable programmable simulation of the interaction of a measurement apparatus with a dynamical quantum system, to explore MIPT phenomena over a range of system sizes while retaining quantum coherence. Yet, existing experimental protocols rely on fundamentally nonscalable postselection techniques or direct classical simulation of quantum circuits. Here, we report the scalable observation of finite-size scaling evidence for an observable-sharpening MIPT in monitored quantum circuits in a chain of Yb + 171 ions in Quantinuum’s H1-1 trapped-ion quantum processor. By leveraging an equivalent description as a statistical physics problem, we implement scalable classical algorithms to infer the value of the measured observable from a single experimental shot. This technique enables a truly scalable protocol to observe observable-sharpening MIPTs in generic classes of circuits that cannot be directly classically simulated and also provides enhanced means to detect and suppress errors in the quantum simulation. Published by the American Physical Society 2024During a quantum measurement, superpositions of states with different observable properties probabilistically collapse into one with a sharp value of the measured observable. In macroscopic quantum systems, this collapse arises via a continuous measurement-induced phase transition (MIPT) at a critical value of the strength of interaction with the measurement apparatus. MIPTs lie outside established paradigms for equilibrium or nonequilibrium critical phenomena and delineate distinct, stable dynamical and computational phases of matter. Quantum computers enable programmable simulation of the interaction of a measurement apparatus with a dynamical quantum system, to explore MIPT phenomena over a range of system sizes while retaining quantum coherence. Yet, existing experimental protocols rely on fundamentally nonscalable postselection techniques or direct classical simulation of quantum circuits. Here, we report the scalable observation of finite-size scaling evidence for an observable-sharpening MIPT in monitored quantum circuits in a chain of Yb + 171 ions in Quantinuum’s H1-1 trapped-ion quantum processor. By leveraging an equivalent description as a statistical physics problem, we implement scalable classical algorithms to infer the value of the measured observable from a single experimental shot. This technique enables a truly scalable protocol to observe observable-sharpening MIPTs in generic classes of circuits that cannot be directly classically simulated and also provides enhanced means to detect and suppress errors in the quantum simulation. Published by the American Physical Society 2024

arXiv:2311.00058Physical Review XOct 15, 202422 citations

Quantum Phase Estimation

Osama M. Raisuddin, Suvranu De

Springer eBooksNov 14, 20250 citations

N

electrons. In particular, we characterize the detected scaling of the phase-jump rate with the number of electrons.