Certified randomness from quantum speed limits

TL;DR

This paper demonstrates that quantum speed limits can be used to generate certified randomness in a device-independent manner, relying only on energy uncertainty bounds and timing choices, with potential experimental implementations.

Contribution

It introduces a novel protocol leveraging quantum speed limits for certified randomness generation without detailed device assumptions.

Findings

Randomness can be certified from energy uncertainty bounds.

Single-mode coherent states can produce certified randomness.

The approach extends semi-device-independent protocols and relates to time-energy uncertainty.

Abstract

Quantum speed limits are usually regarded as fundamental restrictions, constraining the amount of computation that can be achieved within some given time and energy. Complementary to this intuition, here we show that these limitations are also of operational value: they enable the secure generation of certified randomness. We consider a prepare-and-measure scenario with some (experimentally determined or promised) upper bound on the energy uncertainty of the average prepared quantum state, but without any further assumptions on the devices, Hilbert space or Hamiltonian. Given that we can freely choose the time at which to apply the untrusted preparation procedure, we show that this scenario admits the generation of randomness that is secure against adversaries with additional classical information. We show how to determine the amount of certified randomness given the observed correlations, discuss how interactions with the environment are taken into account, and sketch a conceivable experimental implementation. In particular, we show that single-mode coherent states admit this kind of certification of non-zero randomness in some parameter regimes, reinforcing existing demonstrations of nonclassicality in the simple harmonic oscillator. Our results extend earlier efforts to devise semi-device-independent protocols grounded in reasonable physical assumptions, and they contribute to the understanding of time-energy uncertainty relations via their operational consequences.