Experimental demonstration of sequential quantum random access codes

Foletto, Giulio; Calderaro, Luca; Vallone, Giuseppe; Villoresi, Paolo

doi:10.1103/physrevresearch.2.033205

Cited by 41 publications

(36 citation statements)

References 28 publications

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“…Recently, it has been exploited for sequential protocols, in which a system undergoes multiple measurements without ever completely collapsing or losing its useful quantum features, which can be harvested repeatedly. In this manner, Bell inequalities can be violated more times [36][37][38][39][40], quantum random access codes can be used by two parties [41,42], and quantum instruments can be tested [43]. More important for this work is using weak measurements to produce random bits from the same physical system repeatedly [44,45].…”

Section: Introductionmentioning

confidence: 99%

Experimental test of sequential weak measurements for certified quantum randomness extraction

et al. 2021

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Quantum nonlocality offers a secure way to produce random numbers: Their unpredictability is intrinsic and can be certified just by observing the statistic of the measurement outcomes, without assumptions on how they are produced. To do this, entangled pairs are generated and measured to violate a Bell inequality with the outcome statistics. However, after a projective quantum measurement, entanglement is entirely destroyed and cannot be used again. This fact poses an upper bound to the amount of randomness that can be produced from each quantum state when projective measurements are employed. Instead, by using weak measurements, some entanglement can be maintained and reutilized, and a sequence of weak measurements can extract an unbounded amount of randomness from a single state as predicted in Phys. Rev. A 95, 020102(R) (2017). We study the feasibility of these weak measurements, analyze the robustness to imperfections in the quantum state they are applied to, and then test them using an optical setup based on polarization-entangled photon pairs. We show that the weak measurements are realizable, but can improve the performance of randomness generation only in close-to-ideal conditions.

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Section: Introductionmentioning

confidence: 99%

Experimental test of sequential weak measurements for certified quantum randomness extraction

et al. 2021

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“…This has also been experimentally demonstrated [10,11]. Moreover, shared quantum correlations have recently also been studied in other tasks such as entanglement witnessing [12], quantum steering [13,14] and a semidevice-independent setting [15][16][17][18].…”

Section: Introductionmentioning

confidence: 84%

Noise-robust preparation contextuality shared between any number of observers via unsharp measurements

Anwer

Wilson

Silva

et al. 2021

Quantum

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Multiple observers who independently harvest nonclassical correlations from a single physical system share the system's ability to enable quantum correlations. We show that any number of independent observers can share the preparation contextual outcome statistics enabled by state ensembles in quantum theory. Furthermore, we show that even in the presence of any amount of white noise, there exists quantum ensembles that enable such shared preparation contextuality. The findings are experimentally realised by applying sequential unsharp measurements to an optical qubit ensemble which reveals three shared demonstrations of preparation contextuality.

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“…The 2 → 1 and 3 → 1 QRACs were first experimentally demonstrated in [56]. See [21,25,42,59,61] for subsequent demonstrations.…”

Section: Introductionmentioning

confidence: 99%

Quantum Random Access Codes for Boolean Functions

Doriguello

Montanaro

2021

Quantum

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An n↦pm random access code (RAC) is an encoding of n bits into m bits such that any initial bit can be recovered with probability at least p, while in a quantum RAC (QRAC), the n bits are encoded into m qubits. Since its proposal, the idea of RACs was generalized in many different ways, e.g. allowing the use of shared entanglement (called entanglement-assisted random access code, or simply EARAC) or recovering multiple bits instead of one. In this paper we generalize the idea of RACs to recovering the value of a given Boolean function f on any subset of fixed size of the initial bits, which we call f-random access codes. We study and give protocols for f-random access codes with classical (f-RAC) and quantum (f-QRAC) encoding, together with many different resources, e.g. private or shared randomness, shared entanglement (f-EARAC) and Popescu-Rohrlich boxes (f-PRRAC). The success probability of our protocols is characterized by the noise stability of the Boolean function f. Moreover, we give an upper bound on the success probability of any f-QRAC with shared randomness that matches its success probability up to a multiplicative constant (and f-RACs by extension), meaning that quantum protocols can only achieve a limited advantage over their classical counterparts.

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Experimental demonstration of sequential quantum random access codes

Cited by 41 publications

References 28 publications

Experimental test of sequential weak measurements for certified quantum randomness extraction

Experimental test of sequential weak measurements for certified quantum randomness extraction

Noise-robust preparation contextuality shared between any number of observers via unsharp measurements

Quantum Random Access Codes for Boolean Functions

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