The recent years have seen a growing interest in quantum codes in three
dimensions (3D). One of the earliest proposed 3D quantum codes is the 3D toric
code. It has been shown that 3D color codes can be mapped to 3D toric codes.
The 3D toric code on cubic lattice is also a building block for the welded code
which has highest energy barrier to date. Although well known, the performance
of the 3D toric code has not been studied extensively. In this paper, we

In the quantum control process, arbitrary pure or mixed initial states need
to be protected from amplitude damping through the noise channel using
measurements and quantum control. However, how to achieve it on a two-qubit
quantum system remains a challenge. In this paper, we propose a feed-forward
control approach to protect arbitrary two-qubit pure or mixed initial states
using the weak measurement. A feed-forward operation and measurements are used
before the noise channel, and afterwards a reversed operation and measurements

In this paper, we extend previous studies conducted by the authors in a family of pseudo-Hermitian
Gaussian matrices. Namely, we further the studies of the two pseudo-Hermitian random matrix cases
previously considered, the first of a matrix of order N with two interacting blocks of sizes M and N
  −   M and the second of a chessboard-like structured matrix of order N whose subdiagonals
alternate between Hermiticity and pseudo-Hermiticity. Following an average characteristic polynomial

This paper derives the Feynman rules for the diagrammatic perturbation expansion of the effective
action around an arbitrary solvable problem. The perturbation expansion around a Gaussian theory is
well-known and composed of one-line irreducible diagrams only. For the expansions around an
arbitrary, non-Gaussian problem, we show that a more general class of irreducible diagrams remains
in addition to a second set of diagrams that has no analogue in the Gaussian case. The effective

We consider entanglement-assisted (EA) private communication over a quantum broadcast channel, in
which there is a single sender and multiple receivers. We divide the receivers into two sets: the
decoding set and the malicious set. The decoding set and the malicious set can either be disjoint or
can have a finite intersection. For simplicity, we say that a single party Bob has access to the
decoding set and another party Eve has access to the malicious set, and both Eve and Bob have access

The quantum relative entropy is a measure of the distinguishability of two quantum states, and it is
a unifying concept in quantum information theory: many information measures such as entropy,
conditional entropy, mutual information, and entanglement measures can be realized from it. As such,
there has been broad interest in generalizing the notion to further understand its most basic
properties, one of which is the data processing inequality. The quantum f -divergence of Petz is one

We explain how to incorporate the action of local integrals of motion into the fermionic basis for
the sine-Gordon model and its UV conformal field theory. Examples are presented up to level 4.
Numerical computation supports the results. Possible applications are discussed.

Author(s): J. F. Haase, P. J. Vetter, T. Unden, A. Smirne, J. Rosskopf, B. Naydenov, A. Stacey, F. Jelezko, M. B. Plenio, and S. F. Huelga
We present a flexible scheme to realize non-Markovian dynamics of an electronic spin qubit, using a nitrogen-vacancy center in diamond where the inherent nitrogen spin serves as a regulator of the dynamics. By changing the population of the nitrogen spin, we show that we can smoothly tune the non-Ma...
[Phys. Rev. Lett. 121, 060401] Published Thu Aug 09, 2018

Exciton formation leads to J-bands in solid pentacene. Describing these
exciton bands represents a challenge for both time-dependent (TD)
density-functional theory (DFT) and for its semiempirical analogue, namely for
TD density-functional tight binding (DFTB) for three reasons (i) solid
pentacene and pentacene aggregates are bound only by van der Waals forces which
are notoriously difficult to describe with DFT and DFTB, (ii) the proper
description of the long-range coupling between molecules, needed to describe

The study of transformations among pure states via Local Operations assisted
by Classical Communication (LOCC) plays a central role in entanglement theory.
The main emphasis of these investigations is on the deterministic, or
probabilistic transformations between two states and mainly tools from linear
algebra are employed. Here, we go one step beyond that and analyze all optimal
protocols. We show that for all bipartite and almost all multipartite (of