We investigate the entanglement measures of tripartite W-State and GHZ-state
in noninertial frame through the coordinate transformation between Minkowski
and Rindler. First it is shown that all three qubits undergo in a uniform
acceleration $a$ of W-State, we find that the one-tangle, two-tangle, and
$\pi$-tangle decrease when the acceleration parameter $r$ increases, and the
two-tangle cannot arrive to infinity of the acceleration. Next we show that the

Much of modern metrology and communication technology encodes information in
electromagnetic waves, typically as an amplitude or phase. While current
hardware can perform near-ideal measurements of photon number or field
amplitude, to date no device exists that can even in principle perform an ideal
phase measurement. In this work, we implement a single-shot canonical phase
measurement on a one-photon wave packet, which surpasses the current standard
of heterodyne detection and is optimal for single-shot phase estimation. By

We analyze the dynamics of multiparticle discrete-time quantum walk on the
two-dimensional lattice, with an interaction inspired on a classical model for
gas collision, called HPP model. In this classical model, the direction of
motion changes only when the particles collide head-on, preserving momentum and
energy. In our quantum model, the dynamics is driven by the usual quantum-walk
evolution operator if the particles are on different nodes, and is driven by

Quantum annealing is a heuristic algorithm for solving combinatorial
optimization problems, and D-Wave Systems Inc. has developed hardware for
implementing this algorithm. The current version of the D-Wave quantum annealer
can solve unconstrained binary optimization problems with a limited number of
binary variables, although cost functions of many practical problems are
defined by a large number of integer variables. To solve these problems with
the quantum annealer, the integer variables are generally binarized with

We theoretically analyze the performance of the nuclear magnetic resonance
(NMR) spectroscopy with a superconducting flux qubit (FQ). Such NMR with the FQ
is attractive because of the possibility to detect the relatively small number
of nuclear spins in a local region ($\sim\mu$m) with low temperatures ($\sim$
mK) and low magnetic fields ($\sim$ mT), in which other types of quantum
sensing schemes cannot easily access. A sample containing nuclear spins is

We present a novel continuous-time control strategy to exponentially
stabilize an eigenstate of a Quantum Non-Demolition (QND) measurement operator.
In open-loop, the system converges to a random eigenstate of the measurement
operator. The role of the feedback is to prepare a prescribed QND eigenstate
with unit probability. To achieve this we introduce the use of Brownian motion
to drive the unitary control actions; the feedback loop just adapts the
amplitude of this Brownian noise input as a function of the system state.

Entanglement is a fundamental resource for quantum information science.
However, bipartite entanglement is destroyed when one particle is sharply
measured, which occurs in most applications. Here we experimentally show that,
if instead of sharp measurements, one performs many sequential unsharp
measurements on one particle which are suitably chosen depending on the
previous outcomes, then entanglement is preserved and can reveal quantum
correlations through measurements on the second particle. Specifically, we

We study the subradiant collective states of a periodic chain of two-level
atoms with either transversal or longitudinal transition dipole moments with
respect to the chain axis. We show that long-lived subradiant states can be
obtained for the transversal polarization by properly choosing the chain period
for a given number of atoms in the case of no open diffraction channels. These
highly subradiant states have a linewidth that decreases with the number of

The theory of quantum thermodynamics investigates how the concepts of heat,
work, and temperature can be carried over to the quantum realm, where
fluctuations and randomness are fundamentally unavoidable. Of particular
practical relevance is the investigation of quantum thermal machines: Machines
that use the flow of heat in order to perform some useful task. In this
lectures series, we give a brief introduction into how the laws of
thermodynamics arise from quantum theory and how thermal machines can be

We cast diffraction-based interferometry in the framework of post-selected
unitary description towards enabling it as a platform for quantum information
processing. We express slit-diffraction as an infinite-dimensional
transformation and truncate it to a finite-dimensional transfer matrix by
post-selecting modes. Using such a framework with classical fields, a
customized double-slit setup is effectively a lossy beam splitter in a
post-selected sense. Diffraction optics provides a robust alternative to