All

Photonic quantum memory using intra-atomic frequency comb. (arXiv:1810.07617v1 [quant-ph])

Photonic quantum memory, such as atomic frequency comb (AFC), is essential to
make photonic quantum computation and long distance quantum communication
scalable and feasible. In standard AFC the frequency of different atoms must be
stable relative to each other which presents difficulties in realizing the
quantum memory. Here we propose a quantum memory using intra-atomic frequency
comb which does not require frequency stabilization. We show that the
transitions between two degenerate energy levels of a single atom can be used

<i>Dephrasure</i> Channel and Superadditivity of Coherent Information

Author(s): Felix Leditzky, Debbie Leung, and Graeme Smith
The quantum capacity of a quantum channel captures its capability for noiseless quantum communication. It lies at the heart of quantum information theory. Unfortunately, our poor understanding of nonadditivity of coherent information makes it hard to understand the quantum capacity of all but very s...
[Phys. Rev. Lett. 121, 160501] Published Wed Oct 17, 2018

Geometrical Bounds on Irreversibility in Open Quantum Systems

Author(s): Luca Mancino, Vasco Cavina, Antonella De Pasquale, Marco Sbroscia, Robert I. Booth, Emanuele Roccia, Ilaria Gianani, Vittorio Giovannetti, and Marco Barbieri
Theoretical bounds on irreversible entropy production in a thermalizing quantum system are supported by experiments simulating the thermalization of a qubit using a quantum photonic architecture.
[Phys. Rev. Lett. 121, 160602] Published Wed Oct 17, 2018

Hydrodynamic Diffusion in Integrable Systems

Author(s): Jacopo De Nardis, Denis Bernard, and Benjamin Doyon
We show that hydrodynamic diffusion is generically present in many-body, one-dimensional interacting quantum and classical integrable models. We extend the recently developed generalized hydrodynamic (GHD) to include terms of Navier-Stokes type, which leads to positive entropy production and diffusi...
[Phys. Rev. Lett. 121, 160603] Published Wed Oct 17, 2018

Experimental Determination of Irreversible Entropy Production in out-of-Equilibrium Mesoscopic Quantum Systems

Author(s): M. Brunelli, L. Fusco, R. Landig, W. Wieczorek, J. Hoelscher-Obermaier, G. Landi, F. L. Semião, A. Ferraro, N. Kiesel, T. Donner, G. De Chiara, and M. Paternostro
Physicists observe entropy production in two intermediate-scale quantum systems, indicating that the systems have undergone an irreversible process.
[Phys. Rev. Lett. 121, 160604] Published Wed Oct 17, 2018

Dynamics of a Magnetic Needle Magnetometer: Sensitivity to Landau-Lifshitz-Gilbert Damping

Author(s): Y. B. Band, Y. Avishai, and Alexander Shnirman
An analysis of a single-domain magnetic needle (MN) in the presence of an external magnetic field $\mathbf{B}$ is carried out with the aim of achieving a high-precision magnetometer. We determine the uncertainty $\mathrm{Δ}B$ of such a device due to Gilbert dissipation and the associated internal ma...
[Phys. Rev. Lett. 121, 160801] Published Wed Oct 17, 2018

Secure quantum communication in the presence of phase- and polarization-dependent loss

Author(s): Chenyang Li, Marcos Curty, Feihu Xu, Olinka Bedroya, and Hoi-Kwong Lo
Silicon photonics holds the promise of the miniaturization of quantum communication devices. Recently, silicon chip optical transmitters for quantum key distribution (QKD) have been built and demonstrated experimentally. Nonetheless, these silicon chips suffer substantial phase- and polarization-dep...
[Phys. Rev. A 98, 042324] Published Wed Oct 17, 2018

Generic Emergence of Objectivity of Observables in Infinite Dimensions

Author(s): Paul A. Knott, Tommaso Tufarelli, Marco Piani, and Gerardo Adesso
Quantum Darwinism posits that information becomes objective whenever multiple observers indirectly probe a quantum system by each measuring a fraction of the environment. It was recently shown that objectivity of observables emerges generically from the mathematical structure of quantum mechanics, w...
[Phys. Rev. Lett. 121, 160401] Published Wed Oct 17, 2018

Quantum probe spectroscopy for cold atomic systems. (arXiv:1804.09237v2 [cond-mat.quant-gas] UPDATED)

We study a two-level impurity coupled locally to a quantum gas on an optical
lattice. For state-dependent interactions between the impurity and the gas, we
show that its evolution encodes information on the local excitation spectrum of
gas at the coupling site. Based on this, we design a nondestructive method to
probe the system's excitations in a broad range of energies by measuring the
state of the probe using standard atom optics methods. We illustrate our

Realism about the Wave Function. (arXiv:1810.07010v1 [quant-ph])

A century after the discovery of quantum mechanics, the meaning of quantum
mechanics still remains elusive. This is largely due to the puzzling nature of
the wave function, the central object in quantum mechanics. If we are realists
about quantum mechanics, how should we understand the wave function? What does
it represent? What is its physical meaning? Answering these questions would
improve our understanding of what it means to be a realist about quantum
mechanics. In this survey article, I review and compare several realist