We derive a Lindblad master equation that approximates the dynamics of a
Lipkin-Meshkov-Glick (LMG) model weakly coupled to a bosonic bath. By studying
the time evolution of operators under the adjoint master equation we prove
that, for large system sizes, these operators attain their thermal equilibrium
expectation values in the long-time limit, and we calculate the rate at which
these values are approached. Integrability of the LMG model prevents
thermalization in the absence of a bath, and our work provides an explicit

The field of quantum information has matured and various protocols
implementing a quantum computer are being pursued. Most similar to a classical
computer is the circuit model. In 2007 Aharonov et al. showed the equivalence
between the circuit model and a quantum annealer, and with this proofed the
universality of quantum annealing. Here the system starts in an easily
preparable ground state and evolves adiabatically to a final ground state which
yields the solution of the computational problem. However, equivalence with the

We consider a generic Fibonacci topological wave function on a square
lattice, and the norm of this wave function can be mapped into the partition
function of two-coupled $\phi ^{2}$-state Potts models with $\phi
=(\sqrt{5}+1)/2$ as the golden ratio. A global phase diagram is thus
established to display non-abelian topological phase transitions. The Fibonacci
topological phase corresponds to an emergent new phase of the two-coupled Potts
models, and continuously change into two non-topological phases separately,

We propose a scheme for generating arbitrary quantum states in a mechanical
resonator using tuneable three-body interactions with two superconducting
qubits. The coupling relies on embedding a suspended nanobeam in one of the
arms of a superconducting quantum interference device that galvanically
connects two transmon qubits, in combination with an in-plane magnetic field.
Using state-of-the-art parameters and single-qubit operations, we demonstrate
the possibility of ground-state cooling as well as high-fidelity preparation of

We show how the photon statistics emitted by a large variety of light-matter
systems under weak coherent driving can be understood, to lowest order in the
driving, in the framework of an admixture of (or interference between) a
squeezed state and a coherent state, with the resulting state accounting for
all bunching and antibunching features. One can further identify two mechanisms
that produce resonances for the photon correlations: i) conventional statistics

Measurement processes can be separated into an entangling interaction between
the system and a meter and a subsequent read-out of the meter state that does
not involve any further interactions with the system. In the interval between
these two stages, the system and the meter are in an entangled state that
encodes all possible effects of the read-out in the form of non-local quantum
correlations between the system and the meter. Here, we show that the
entanglement generated in the system-meter interaction expresses a fundamental

We study efficient quantum error correction schemes for the fully correlated
channel on an $n$-qubit system with error operators that assume the form
$\sigma_x^{\otimes n}$, $\sigma_y^{\otimes n}$, $\sigma_z^{\otimes n}$. In
particular, when $n=2k+1$ is odd, we describe a quantum error correction scheme
using one arbitrary qubit $\sigma$ to protect the data state $\rho$ in the
$2k$-qubit system such that only $3k$ CNOT gates (each with one control bit and

The transport of a particle in the presence of a potential that changes
periodically in space and in time can be characterized by the amount of work
needed to shift a particle by a single spatial period of the potential. In
general, this amount of work, when averaged over a single temporal period of
the potential, can take any value in a continuous fashion. Here we present a
topological effect inducing the quantization of the average work. We find that
this work is equal to the first Chern number calculated in a unit cell of a

In this paper, we present a gradient algorithm for identifying unknown
parameters in an open quantum system from the measurements of time traces of
local observables. The open system dynamics is described by a general Markovian
master equation based on which the Hamiltonian identification problem can be
formulated as minimizing the distance between the real time traces of the
observables and those predicted by the master equation. The unknown parameters
can then be learned with a gradient descent algorithm from the measurement

The quantum Hall states at filling factors 5/2 and 7/2 are expected to have
Abelian charge e/2 quasiparticles and non-Abelian charge e/4 quasiparticles. We
test this by measuring resistance oscillations as a function of magnetic field
in quantum Hall Fabry-Perot interferometers. At filling factor 5/2 they have
four dominant frequencies, as expected for transport due to these two types of
quasiparticles. At 7/2 filling a different set of frequencies is expected, and