Observation of partial and infinite-temperature thermalization induced by repeated measurements on a quantum hardware

Year: 2023

Authors: Santini Alessandro; Solfanelli Andrea; Gherardini Stefano; Giachetti Guido

Autors Affiliation: SISSA, Via Bonomea 265, I-34136 Trieste, Italy; INFN Sez Trieste, Via Bonomea 265, I-34136 Trieste, Italy; Italian Inst Technol, Ctr Life Nanoneurosci, Viale Regina Elena 291, I-00161 Rome, Italy; CNR, Ist Nazl Ottica, Area Sci Pk, I-34149 Trieste, Italy; Abdus Salam Int Ctr Theoret Phys ICTP, Str Costiera 11, I-34151 Trieste, Italy; Univ Paris Cergy, LPTM, Ave Adolphe Chauvin 2, F-95300 Pontoise, France.

Abstract: On a quantum superconducting processor we observe partial and infinite-temperature thermalization induced by a sequence of repeated quantum projective measurements, interspersed by a unitary (Hamiltonian) evolution. Specifically, on a qubit and two-qubit systems, we test the state convergence of a monitored quantum system in the limit of a large number of quantum measurements, depending on the non-commutativity of the Hamiltonian and the measurement observable. When the Hamiltonian and observable do not commute, the convergence is uniform towards the infinite-temperature state. Conversely, whenever the two operators have one or more eigenvectors in common in their spectral decomposition, the state of the monitored system converges differently in the subspaces spanned by the measurement observable eigenstates. As a result, we show that the convergence does not tend to a completely mixed (infinite-temperature) state, but to a block-diagonal state in the observable basis, with a finite effective temperature in each measurement subspace. Finally, we quantify the effects of the quantum hardware noise on the data by modelling them by means of depolarizing quantum channels.

Journal/Review: JOURNAL OF PHYSICS COMMUNICATIONS

Volume: 7 (6)      Pages from: 065007-1  to: 065007-16

More Information: We acknowledge the use of IBM Quantum services for this work [78]. The views expressed are those of the authors and do not reflect the official policy or position of IBM or the IBM Quantum team. In this paper, we used ibm_lagos which is a IBM Quantum Falcon r5.11H processor. S G acknowledges financial support from the MISTI Global Seed Funds MIT-FVG Collaboration Grant Non-Equilibrium Thermodynamics of Dissipative Quantum Systems (NETDQS)´, and the PNRR MUR project PE0000023-NQSTI.
KeyWords: quantum measurements, quantum zeno effect, quantum computing, quantum hardware, noise model, quantum thermalization
DOI: 10.1088/2399-6528/acdd4f

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