# All

## Quantum enhanced estimation of diffusion. (arXiv:1901.02497v2 [quant-ph] UPDATED)

Momentum diffusion is a possible mechanism for driving macroscopic quantum
systems towards classical behaviour. Experimental tests of this hypothesis rely
on a precise estimation of the strength of this diffusion. We show that
quantum-mechanical squeezing offers significant improvements, including when
measuring position. For instance, with 10dB of mechanical squeezing,
experiments would require a tenth of proposed free-fall times. Momentum
measurement is better by an additional factor of three, while another

## Entanglement Wedge Reconstruction and the Information Paradox. (arXiv:1905.08255v1 [hep-th])

When absorbing boundary conditions are used to evaporate a black hole in
AdS/CFT, we show that there is a phase transition in the location of the
quantum Ryu-Takayanagi surface, at precisely the Page time. The new RT surface
lies slightly inside the event horizon, at an infalling time approximately the
scrambling time $\beta/2\pi \log S_{BH}$ into the past. We can immediately
derive the Page curve, using the Ryu-Takayanagi formula, and the
Hayden-Preskill decoding criterion, using entanglement wedge reconstruction.

## A statistical mechanical analysis on the bound state solution of an energy-dependent deformed Hulth\'en potential energy. (arXiv:1905.08430v1 [quant-ph])

In this article, we investigate the bound state solution of the Klein Gordon
equation under mixed vector and scalar coupling of an energy-dependent deformed
Hulth\'en potential in D-dimensions. We obtain a transcendental equation after
we impose the boundary conditions. We calculate energy spectra in four
different limits and in arbitrary dimension via the Newton-Raphson method.
Then, we use a statistical method, namely canonical partition function, and

## Tube algebras, excitations statistics and compactification in gauge models of topological phases. (arXiv:1905.08673v1 [cond-mat.str-el])

We consider lattice Hamiltonian realizations of ($d$+1)-dimensional
Dijkgraaf-Witten theory. In (2+1)d, it is well-known that the Hamiltonian
yields point-like excitations classified by irreducible representations of the
twisted quantum double. This can be confirmed using a tube algebra approach. In
this paper, we propose a generalization of this strategy that is valid in any
dimensions. We then apply the tube algebra approach to derive the algebraic
structure of loop-like excitations in (3+1)d, namely the twisted quantum

## Bloch oscillations of multi-magnon excitations in a Heisenberg XXZ chain. (arXiv:1902.00273v2 [quant-ph] UPDATED)

The studies of multi-magnon excitations will extend our understandings of
quantum magnetism and strongly correlated matters. Here, by using the
time-evolving block decimation algorithm, we investigate the Bloch oscillations
of two-magnon excitations under a gradient magnetic field. Through analyzing
the symmetry of the Hamiltonian, we derive a rigorous and universal relation
between ferromagnetic and anti-ferromagnetic systems. Under strong
interactions, in addition to free-magnon Bloch oscillations, there appear

## The isolated Heisenberg magnet as a quantum time crystal. (arXiv:1905.08266v1 [cond-mat.stat-mech])

Isolated systems consisting of many interacting particles are generally
assumed to relax to a stationary equilibrium state whose macroscopic properties
are described by the laws of thermodynamics and statistical physics. Time
crystals, as first proposed by Wilczek, could defy some of these fundamental
laws and for instance display persistent non-decaying oscillations. They can be
engineered by external driving or contact with an environment, but are believed

## Low-latency switchable coupler for photonic routing. (arXiv:1905.08431v1 [quant-ph])

Photonic switching is a key building block of many optical applications
challenging its development. We report a 2$\times$2 photonic coupler with
arbitrary splitting ratio switchable by a low-voltage electronic signal with 10
GHz bandwidth and tens of nanoseconds latency. The coupler is based on a single
Mach-Zehnder interferometer in dual-wavelength configuration allowing real-time
phase lock with sub-degree stability. The coupler can be set to any splitting

## Entanglement between a diamond spin qubit and a photonic time-bin qubit at telecom wavelength. (arXiv:1905.08676v1 [quant-ph])

We report on the realization and verification of quantum entanglement between
an NV electron spin qubit and a telecom-band photonic qubit. First we generate
entanglement between the spin qubit and a 637 nm photonic time-bin qubit,
followed by photonic quantum frequency conversion that transfers the
entanglement to a 1588 nm photon. We characterize the resulting state by
correlation measurements in different bases and find a lower bound to the Bell
state fidelity of F = 0.77 +/- 0.03. This result presents an important step

## Large-scale multilayer architecture of single-atom arrays with individual addressability. (arXiv:1902.05424v3 [quant-ph] UPDATED)

We report on the realization of large-scale 3D multilayer configurations of
planar arrays of individual neutral atoms with immediate applications in
quantum science and technology: a microlens-generated Talbot optical lattice In
this novel platform, the single-beam illumination of a microlens array
constitutes a structurally robust and wavelength-universal method for the
realization of 3D atom arrays with favourable scaling properties due to the
inherent self-imaging of the focal structure. Thus, 3D scaling comes without

## Gradient-based optimal control of open quantum systems using quantum trajectories and automatic differentiation

Author(s): Mohamed Abdelhafez, David I. Schuster, and Jens Koch
We present a gradient-based optimal-control technique for open quantum systems that utilizes quantum trajectories to simulate the quantum dynamics during optimization. Using trajectories allows for optimizing open systems with less computational cost than the regular density matrix approaches in mos...
[Phys. Rev. A 99, 052327] Published Mon May 20, 2019