Quantum 7, 974 (2023). https://doi.org/10.22331/q-2023-04-13-974 We analyze the barren plateau phenomenon in the variational optimization of quantum circuits inspired by matrix product states (qMPS), tree tensor networks (qTTN), and the multiscale entanglement renormalization ansatz (qMERA). […]
Quantum 7, 973 (2023). https://doi.org/10.22331/q-2023-04-06-973 Continuous-time measurements are instrumental for a multitude of tasks in quantum engineering and quantum control, including the estimation of dynamical parameters of open quantum systems monitored through the environment. However, […]
Quantum 7, 972 (2023). https://doi.org/10.22331/q-2023-04-06-972 Driven quantum systems subject to non-Markovian noise are typically difficult to model even if the noise is classical. We present a systematic method based on generalized cumulant expansions for deriving […]
Quantum 7, 971 (2023). https://doi.org/10.22331/q-2023-04-06-971 We consider how to define a natural probability distribution over worlds within a simple class of deterministic many-worlds theories. This can help us understand the typical properties of worlds within […]
Quantum 7, 970 (2023). https://doi.org/10.22331/q-2023-04-06-970 An adiabatic state preparation technique, called the adiabatic spiral, is proposed for the Heisenberg model. This technique is suitable for implementation on a number of quantum simulation platforms such as […]
Quantum 7, 969 (2023). https://doi.org/10.22331/q-2023-03-30-969 We present an end-to-end and practical randomness amplification and privatisation protocol based on Bell tests. This allows the building of device-independent random number generators which output (near-)perfectly unbiased and private […]
Quantum 7, 968 (2023). https://doi.org/10.22331/q-2023-03-30-968 We compare the proposals that have appeared in the literature to describe a measurement of the time of arrival of a quantum particle at a detector. We show that there […]
Quantum 7, 967 (2023). https://doi.org/10.22331/q-2023-03-30-967 We present a family of electron-based coupled-wire models of bosonic orbifold topological phases, referred to as twist liquids, in two spatial dimensions. All local fermion degrees of freedom are gapped […]
Quantum 7, 966 (2023). https://doi.org/10.22331/q-2023-03-30-966 We study variational quantum algorithms from the perspective of free fermions. By deriving the explicit structure of the associated Lie algebras, we show that the Quantum Approximate Optimization Algorithm (QAOA) […]
Quantum 7, 965 (2023). https://doi.org/10.22331/q-2023-03-30-965 Thanks to common-mode noise rejection, differential configurations are crucial for realistic applications of phase and frequency estimation with atom interferometers. Currently, differential protocols with uncorrelated particles and mode-separable settings reach […]
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