The field of optomechanics provides us with several examples of quantum

photon-phonon interface. In this paper, we theoretically investigate the

generation and manipulation of quantum correlations in a microfabricated

optomechanical array. We consider a system consisting of localized photonic and

phononic modes interacting locally via radiation pressure at each lattice site

with the possibility of hopping of photons and phonons between neighboring

sites. We show that such an interaction can correlate various modes of a driven

# All

We present a new method to compute short-time expectation values in large

collective spin systems with generic Markovian decoherence. Our method is based

on a Taylor expansion of a formal solution to the equations of motion for

Heisenberg operators. This expansion can be truncated at finite order to obtain

virtually exact results at short times that are relevant for metrological

applications such as spin squeezing. In order to evaluate the expansion for

Heisenberg operators, we compute the relevant structure constants of a

In support of the growing interest in quantum computing experimentation,

programmers need new tools to write quantum algorithms as program code.

Compared to debugging classical programs, debugging quantum programs is

difficult because programmers have limited ability to probe the internal states

of quantum programs; those states are difficult to interpret even when

observations exist; and programmers do not yet have guidelines for what to

check for when building quantum programs. In this work, we present quantum

Optical levitation of nanoscale particles has emerged as a platform for

precision measurement. Extremely low damping, together with optical

interferometric position detection, makes possible exquisite force measurement

and promises low-energy tests of fundamental physics. Essential to such

measurement is an understanding of the confidence with which parameters can be

inferred from spectra estimated from the indirect measurement provided by

interferometry. We present an apparatus optimized for sensitivity along one

We theoretically investigate the spectral property of a biphoton state from

multiplexed thermal atomic ensembles. This biphoton state originates from the

cascade emissions, which can be generated by two weak pump fields under

four-wave mixing condition. Under this condition, a signal photon from the

upper transition, chosen in a telecommunication bandwidth, can be generated

along with a correlated idler photon from the lower infrared transition. We can

spectrally shape the biphoton state by multiplexing the atomic ensembles with

We notice that the general PT-symmetric Hamiltonian matrix(N=2) having 6-real

parameters fails to reproduce one parameter PT-symmetric matrix.

Any quantum communication task requires a common reference frame (i.e. phase,

coordinate system). In particular, Quantum Key Distribution requires different

bases for preparation and measurements of states which are obviously based on

the existence of a common frame of reference. Here we show how QKD can be

achieved in the absence of any common frame of reference. We study the

coordinate reference frame, where the two parties do not even share a single

direction, but the method can be generalized to other general frames of

We propose an unconventional scheme for quantum entangled state distribution

(QESD) and quantum state transfer~(QST) based on a fiber-cavity-atom system, in

which three atoms are confined, respectively, in three bimodal cavities

connected with each other by optical fibers. The key feature of the scheme is

the virtual excitation of photons, which yields QESD and QST between the two

atoms in the edge-cavities conditioned on one-step operation only on the atom

Alignment is a geometric relation between pairs of Weyl-Heisenberg SICs, one

in dimension $d$ and another in dimension $d(d-2)$, manifesting a well-founded

conjecture about a number-theoretical connection between the SICs. In this

paper, we prove that if $d$ is even, the SIC in dimension $d(d-2)$ of an

aligned pair can be partitioned into $(d-2)^2$ tight $d^2$-frames of rank

$d(d-1)/2$ and, alternatively, into $d^2$ tight $(d-2)^2$-frames of rank

$(d-1)(d-2)/2$. The corresponding result for odd $d$ is already known, but the

The relative entropy is a measure of the distinguishability of two quantum

states. A great deal of progress has been made in the study of the relative

entropy between an excited state and the vacuum state of a conformal field

theory (CFT) reduced to a spherical region. For example, when the excited state

is a small perturbation of the vacuum state, the relative entropy is known to

have a universal expression for \textit{all} CFT's

\cite{Faulk-GR-entanglement}. Specifically, the perturbative relative entropy