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 […]
Tag: quantumjournal
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 […]
Quantum 5, 507 (2021). https://doi.org/10.22331/q-2021-07-20-507 There has been an intense debate on the question as to whether a quanton, passing through a double-slit, experiences a ‘momentum kick’ due to the act of which-way detection. There […]
Quantum 5, 506 (2021). https://doi.org/10.22331/q-2021-07-19-506 Rutherford scattering is usually described by treating the projectile either classically or as quantum mechanical plane waves. Here we treat them as wave packets and study their head-on collisions with […]
Quantum 5, 505 (2021). https://doi.org/10.22331/q-2021-07-15-505 We study the role of coherence in closed and open quantum batteries. We obtain upper bounds to the work performed or energy exchanged by both closed and open quantum batteries […]
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