Quantum 5, 530 (2021). https://doi.org/10.22331/q-2021-08-27-530 In a quantum world, reference frames are ultimately quantum systems too – but what does it mean to “jump into the perspective of a quantum particle”? In this work, we […]
Category: quantumjournal
Quantum 5, 529 (2021). https://doi.org/10.22331/q-2021-08-20-529 We initiate the study of quantum algorithms for escaping from saddle points with provable guarantee. Given a function $fcolonmathbb{R}^{n}tomathbb{R}$, our quantum algorithm outputs an $epsilon$-approximate second-order stationary point using $tilde{O}(log^{2} […]
Quantum 5, 528 (2021). https://doi.org/10.22331/q-2021-08-19-528 It is well known that by repeatedly measuring a quantum system it is possible to completely freeze its dynamics into a well defined state, a signature of the quantum Zeno […]
Quantum 5, 527 (2021). https://doi.org/10.22331/q-2021-08-19-527 By taking a Poisson limit for a sequence of rare quantum objects, I derive simple formulas for the Uhlmann fidelity, the quantum Chernoff quantity, the relative entropy, and the Helstrom […]
Quantum 5, 526 (2021). https://doi.org/10.22331/q-2021-08-17-526 What is the role of topology in the propagation of quantum light in photonic lattices? We address this question by studying the propagation of squeezed states in a topological one-dimensional […]
Quantum 5, 525 (2021). https://doi.org/10.22331/q-2021-08-17-525 Quantum interference of “clocks”, namely of particles with time-evolving internal degrees of freedom (DOFs), is a promising avenue to test genuine general relativistic effects in quantum systems. The clock acquires […]
Quantum 5, 524 (2021). https://doi.org/10.22331/q-2021-08-16-524 The quantum measurement problem can be regarded as the tension between the two alternative dynamics prescribed by quantum mechanics: the unitary evolution of the wave function and the state-update rule […]
Quantum 5, 523 (2021). https://doi.org/10.22331/q-2021-08-16-523 In the right conditions, removing one particle from a multipartite bound state can make it fall apart. This feature, known as the “Borromean property”, has been recently demonstrated experimentally in […]
Quantum 5, 522 (2021). https://doi.org/10.22331/q-2021-08-09-522 Although quantum channels underlie the dynamics of quantum states, maps which are not physical channels — that is, not completely positive — can often be encountered in settings such as […]
Quantum 5, 521 (2021). https://doi.org/10.22331/q-2021-08-09-521 Covariant codes are quantum codes such that a symmetry transformation on the logical system could be realized by a symmetry transformation on the physical system, usually with limited capability of […]
Recent Comments