Possible limits on superconducting quantum computers from spontaneous wave-function collapse models

Year: 2022

Authors: Vischi M., Ferialdi L., Trombettoni A., Bassi A.

Autors Affiliation: Univ Trieste, Dept Phys, Str Costiera 11, I-34151 Trieste, Italy; Ist Nazl Fis Nucl, Trieste Sect, Via Valerio 2, I-34127 Trieste, Italy; CNR IOM DEMOCRITOS Simulat Ctr, Via Bonomea 265, I-34136 Trieste, Italy; CNR, Natl Inst Opt, Res Unit Trieste, Str Statale 14, I-34149 Trieste, Italy.

Abstract: The continuous spontaneous localization (CSL) model is an alternative formulation of quantum mechanics, which introduces a noise-coupled nonlinearly to the wave function to account for its collapse. We consider CSL effects on quantum computers made of superconducting transmon qubits. As a direct effect CSL reduces quantum superpositions of the computational basis states of the qubits: we show the reduction rate to be negligibly small. However, an indirect effect of CSL, dissipation induced by the noise, also leads transmon qubits to decohere, by generating additional quasiparticles. Since the decoherence rate of transmon qubits depends on the quasiparticle density, by computing their generation rate induced by CSL, we can estimate the corresponding quasiparticle density and thus the limit set by CSL on the performances of transmon quantum computers. We show that CSL could spoil the quantum computation of practical algorithms on large devices. We further explore the possibility of testing CSL effects on superconducting devices.

Journal/Review: PHYSICAL REVIEW B

Volume: 106 (17)      Pages from: 174506-1  to: 174506-16

More Information: Discussions with M. Paternostro and A. Varlamov are gratefully acknowledged. A.B. and L.F. acknowledge fi- nancial support from the H2020 FET Project TEQ (Grant No. 766900) . A.T. and A.B. acknowledge support form the CNR/RS (London) Project ’Testing fundamental theories with ultracold atoms’. A.B. acknowledges the Foundational Questions Institute and Fetzer Franklin Fund, a donor advised fund of Silicon Valley Community Foundation (Grant No. FQXi-RFP-CPW- 2002) , INFN, and the University of Trieste.
KeyWords: Radiation; Bounds
DOI: 10.1103/PhysRevB.106.174506

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