Holographic vacuum energy regularization and corrected entropy of de Sitter space

We propose that the spectrum of the surface area of the apparent horizon (AH) of de Sitter (dS) spacetime leads to corrected temperature and entropy of the dS spacetime, offering new insights into its thermodynamic properties. This is done by employing the spectrum of the AH radius, acquired from the Wheeler--DeWitt (WDW) equation, together with the Stefan--Boltzmann law, the time-energy uncertainty relation, and the unified first law of thermodynamics

Semi-device-independent randomness from d -outcome continuous-variable detection

Recently, semi-device-independent protocols have attracted increasing attention, guaranteeing security with few hypotheses and experimental simplicity. In this paper, we demonstrate a many-outcome scheme with binary phase-shift keying (BPSK) for a semi-device-independent protocol based on the energy assumption. We show in theory that the number of certified random bits of the d-outcome system outperforms the standard scheme (binary outcomes). Furthermore, we compare the results of two well-known measurement schemes, homodyne detection and heterodyne detection. Taking into account the experimental imperfections, we discuss the experimental feasibility of the d-outcome design, and finally, we experimentally validate this approach with an experiment based on BPSK modulation and heterodyne detection

Unbounded randomness from uncharacterized sources

Randomness is a central feature of quantum mechanics and an invaluable resource for both classical and quantum technologies. Commonly, in Device-Independent and Semi-Device-Independent scenarios, randomness is certified using projective measurements, and its amount is bounded by the quantum system's dimension. Here, we propose a Source-Device-Independent protocol, based on Positive Operator Valued Measurement (POVM), which can arbitrarily increase the number of certified bits for any fixed dimension. Additionally, the proposed protocol doesn't require an initial seed and active basis switching, simplifying its experimental implementation and increasing the generation rates. A tight lower-bound on the quantum conditional min-entropy is derived using only the POVM structure and the experimental expectation values, taking into account the quantum side-information. For symmetric POVM on the Bloch sphere, we derive closed-form analytical bounds. Finally, we experimentally demonstrate our method with a compact and simple photonic setup that employs polarization-encoded qubits and POVM up to 6 outcomes.The laws of quantum mechanics allow for the generation of genuine random numbers, but quantum random number generation schemes need additional assumptions on the sources and detection to ensure the security and their generation is limited by the system's dimension. The authors propose and experimentally demonstrate a quantum random number generation scheme based on positive operator valued measurements, lifting the requirement of a trusted source which can arbitrarily increase the number of certified bits for any dimension

Practical Semi-Device-Independent Quantum Random Number Generators

We describe a series of works where different Semi-DI protocols for Quantum Random Number generation are proposed and experimentally realized using photonic systems. These protocols exploit both discrete and continuous variables to generate private randomness

Semi-device independent randomness generation based on quantum state's indistinguishability

Semi-device independent (Semi-DI) quantum random number generators (QRNGs) gained attention for security applications, offering an excellent trade-off between security and generation rate. This paper presents a proof-of-principle time-bin encoding semi-DI QRNG experiments based on a prepare-and-measure scheme. The protocol requires two simple assumptions and a measurable condition: an upper-bound on the prepared pulses' energy. We lower-bound the conditional min-entropy from the energy-bound and the input-output correlation, determining the amount of genuine randomness that can be certified. Moreover, we present a generalized optimization problem for bounding the min-entropy in the case of multiple input and outcomes, in the form of a semidefinite program. The protocol is tested with a simple experimental setup, capable of realizing two configurations for the ternary time-bin encoding scheme. The experimental setup is easy-to-implement and comprises commercially available off-the-shelf components at the telecom wavelength, granting a secure and certifiable entropy source. The combination of ease-of-implementation, scalability, high security level and output-entropy, make our system a promising candidate for commercial QRNGs