Generalized measurements on qubits in quantum randomness certification and expansion

TL;DR

This paper demonstrates experimentally that generalized measurements on qubits can certify more than one bit of quantum randomness per measurement, improving security in quantum cryptography and information processing.

Contribution

It provides the first empirical evidence that generalized measurements can enhance quantum randomness certification and expansion protocols.

Findings

Achieved 1.21 bits of min-entropy from entangled qubits.

Obtained 1.07 bits of min-entropy from single-qubit measurements.

Analyzed finite data protocols using the Entropy Accumulation Theorem.

Abstract

Quantum mechanics has greatly impacted our understanding of the microscopic nature. One of the key concepts of this theory is generalized measurements, which have proven useful in various quantum information processing tasks. However, despite their significance, they have not yet been shown empirically to provide an advantage in quantum randomness certification and expansion protocols. This investigation explores scenarios where generalized measurements can yield more than one bit of certified randomness with a single qubit system measurement on untrusted devices and against a quantum adversary. We compare the robustness of several protocols to exhibit the advantage of exploiting generalized measurements. In our analysis of experimental data, we were able to obtain $1.21$ bits of min-entropy from a measurement taken on one qubit of an entangled state. We also obtained $1.07$ bits of min-entropy from an experiment with quantum state preparation and generalized measurement on a single qubit. We also provide finite data analysis for a protocol using generalized measurements and the Entropy Accumulation Theorem. Our exploration demonstrates the potential of generalized measurements to improve the certification of quantum sources of randomness and enhance the security of quantum cryptographic protocols and other areas of quantum information.