q-2019-12-02-207.pdf (2.46 MB)
Ergodicity probes: using time-fluctuations to measure the Hilbert space dimension
journal contribution
posted on 2023-06-09, 20:12 authored by Charlie Nation, Diego PorrasQuantum devices, such as quantum simulators, quantum annealers, and quantum computers, may be exploited to solve problems beyond what is tractable with classical computers. This may be achieved as the Hilbert space available to perform such `calculations' is far larger than that which may be classically simulated. In practice, however, quantum devices have imperfections, which may limit the accessibility to the whole Hilbert space. We thus determine that the dimension of the space of quantum states that are available to a quantum device is a meaningful measure of its functionality, though unfortunately this quantity cannot be directly experimentally determined. Here we outline an experimentally realisable approach to obtaining the required Hilbert space dimension of such a device to compute its time evolution, by exploiting the thermalization dynamics of a probe qubit. This is achieved by obtaining a fluctuation-dissipation theorem for high-temperature chaotic quantum systems, which facilitates the extraction of information on the Hilbert space dimension via measurements of the decay rate, and time-fluctuations.
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Publication status
- Published
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- Accepted version
Journal
QuantumISSN
2521-327XPublisher
QuantumExternal DOI
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3Page range
207Department affiliated with
- Physics and Astronomy Publications
Research groups affiliated with
- Atomic, Molecular and Optical Physics Research Group Publications
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- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2020-01-10First Open Access (FOA) Date
2020-01-10First Compliant Deposit (FCD) Date
2020-01-09Usage metrics
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