Megahertz-Rate Semi-Device-Independent Quantum Random Number Generators Based on Unambiguous State Discrimination

Abstract

An approach to quantum random number generation based on unambiguous quantum state discrimination is developed. We consider a prepare-and-measure protocol, where two nonorthogonal quantum states can be prepared, and a measurement device aims at unambiguously discriminating between them. Because the states are nonorthogonal, this necessarily leads to a minimal rate of inconclusive events whose occurrence must be genuinely random and which provide the randomness source that we exploit. Our protocol is semi-device-independent in the sense that the output entropy can be lower bounded based on experimental data and a few general assumptions about the setup alone. It is also practically relevant, which we demonstrate by realizing a simple optical implementation, achieving rates of 16.5 Mbits=s. Combining ease of implementation, a high rate, and a real-time entropy estimation, our protocol represents a promising approach intermediate between fully device-independent protocols and commercial quantum random number generators.

Semi-device-independent characterization of quantum measurements under a minimum overlap assumption

“…As a more concrete example, for δ = 0.9, the behavior of the optimal USD measurement can only certify 0.15 bit of randomness (computed via a SDP as in Ref. [30]).…”

“…Finally, Ref. [30] assumed a lower bound on the overlap between the prepared quantum states. Moreover, Ref.…”

Experimental Self-Characterization of Quantum Measurements

“…without assuming the internal workings of the apparatus used. These self-testing methods originated from ensuring secure cryptography [9] and were then utilized to bound dimensionality [13,14], generate random numbers [15][16][17] and verify quantum computers [18]. In this line, DI tests are typically based on a witness involving linear combinations of observed probabilities so only a specific class of states and measurements can be selftested within this regime.…”

“…Future works will investigate the range for high-dimensional systems and entangled states. We expect the range-based techniques will become a new means for specifying quantum systems and mapping detector response [27], and find their applications in a wide range of quantum information tasks such as cryptography, random number generation [17] and metrology, especially where calibrating measuring apparatus is required in advance.…”

Self-testing quantum random-number generator based on an energy bound

“…This has motivated the development of alternative solutions (see e.g. [8][9][10][11][12][13][14][15][16][17][18]), often referred to as semi-DI (or self-testing), exploring intermediate possibilities between the fully DI setting and the more standard "device-dependent" approaches to QRNG, which require a full characterisation of the devices (see e.g. [19][20][21][22][23][24]).…”