Quantum 5, 517 (2021). https://doi.org/10.22331/q-2021-08-05-517 The surface code is a leading candidate quantum error correcting code, owing to its high threshold, and compatibility with existing experimental architectures. Bravyi et al. (2006) showed that encoding a […]
Quantum 5, 516 (2021). https://doi.org/10.22331/q-2021-08-03-516 Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that enables the complete characterization of a […]
Quantum 5, 515 (2021). https://doi.org/10.22331/q-2021-08-03-515 We study the relation of causal influence between input systems of a reversible evolution and its output systems, in the context of operational probabilistic theories. We analyse two different definitions […]
Quantum 5, 514 (2021). https://doi.org/10.22331/q-2021-08-03-514 Given a closed quantum system, the states that can be reached with a cyclic process are those with the same spectrum as the initial state. Here we prove that, under […]
Quantum 5, 513 (2021). https://doi.org/10.22331/q-2021-07-28-513 This paper proposes a highly efficient quantum algorithm for portfolio optimisation targeted at near-term noisy intermediate-scale quantum computers. Recent work by Hodson et al. (2019) explored potential application of hybrid […]
Quantum 5, 512 (2021). https://doi.org/10.22331/q-2021-07-28-512 We introduce a novel hybrid algorithm to simulate the real-time evolution of quantum systems using parameterized quantum circuits. The method, named “projected – Variational Quantum Dynamics” (p-VQD) realizes an iterative, […]
Quantum 5, 511 (2021). https://doi.org/10.22331/q-2021-07-28-511 The causal structure of a unitary transformation is the set of relations of possible influence between any input subsystem and any output subsystem. We study whether such causal structure can […]
Quantum 5, 510 (2021). https://doi.org/10.22331/q-2021-07-27-510 We present a general framework for modifying quantum approximate optimization algorithms (QAOA) to solve constrained network flow problems. By exploiting an analogy between flow-constraints and Gauss’ law for electromagnetism, we […]
Quantum 5, 509 (2021). https://doi.org/10.22331/q-2021-07-26-509 The ability to simulate a fermionic system on a quantum computer is expected to revolutionize chemical engineering, materials design, nuclear physics, to name a few. Thus, optimizing the simulation circuits […]
Quantum 5, 508 (2021). https://doi.org/10.22331/q-2021-07-22-508 In general relativity, the description of spacetime relies on idealised rods and clocks, which identify a reference frame. In any concrete scenario, reference frames are associated to physical systems, which […]
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