We introduce a measure of quantum non-Gaussianity (QNG) for those quantum

states not accessible by a mixture of Gaussian states in terms of quantum

relative entropy. Specifically, we employ a convex-roof extension using all

possible mixed-state decompositions beyond the usual pure-state decompositions.

We prove that this approach brings a QNG measure fulfilling the properties

desired as a proper monotone under Gaussian channels and conditional Gaussian

operations. As an illustration, we explicitly calculate QNG for the noisy

# All

Blind quantum computation (BQC) allows that a client who has limited quantum

abilities can delegate quantum computation to a server who has advanced quantum

technologies but learns nothing about the client's private information. For

example, measurement-based model can guarantee privacy of client's inputs,

quantum algorithms and outputs. However, it still remains a challenge to

directly encrypt quantum algorithms in circuits model. To solve the problem, we

We study the reduced time-evolution of open quantum systems by combining

quantum-information and statistical field theory. Inspired by prior work [EPL

102, 60001 (2013) and Phys. Rev. Lett. 111, 050402 (2013)] we establish the

explicit structure guaranteeing the complete positivity (CP) and

trace-preservation (TP) of the real-time evolution expansion in terms of the

microscopic system-environment coupling.

The toric code is known to be equivalent to free fermions. This paper

presents explicit local unitary transformations that map the $\mathbb{Z}_2$

toric and surface code --- the open boundary equivalent of the toric code ---

to fermions. Through this construction it is shown that the surface code can be

mapped to a set of free fermion modes, while the toric code requires additional

fermionic symmetry operators. Finally, it is demonstrated how the anyonic

statistics of these codes are encoded in the fermionic representations.

We study entanglement of spin degrees of freedom with continuous one in

supersymmetric (SUSY) quantum mechanics. Concurrence is determined by mean

value of spin and is calculated explicitly for SUSY states. We show that

eigenstates of supercharges are maximally entangled. As an example the

entanglement of atom state with photon state and SUSY in Jaynes-Cummings model

are considered.

We report on a highly controllable, hybrid quantum system consisting of cold

Rydberg atoms and an optical nanofiber interface. Using a two-photon excitation

process to drive $5S \rightarrow 5P \rightarrow 29D $ transitions in $^{87}$Rb,

we observe both coherent and incoherent excitation of the Rydberg atoms at

submicron distances from the fiber surface. The $5S \rightarrow 5D$ transition

is mediated by the cooling laser at 780 nm, while the $5D \rightarrow 29D$

Helium nanodroplets doped with polar molecules are studied by electrostatic

deflection. This broadly applicable method allows even polyatomic molecules to

attain sub-Kelvin temperatures and nearly full orientation in the field. The

resulting intense force from the field gradient strongly deflects even droplets

with tens of thousands of atoms, the most massive neutral systems studied by

beam "deflectometry." We use the deflections to extract droplet size

distributions. Moreover, since each host droplet deflects according to its

Out-of-time-ordered correlators (OTOCs) have been proposed as a tool to

witness quantum information scrambling in many-body system dynamics. These

correlators can be understood as averages over nonclassical multi-time

quasi-probability distributions (QPDs). These QPDs have more information, and

their nonclassical features witness quantum information scrambling in a more

nuanced way. However, their high dimensionality and nonclassicality make QPDs

challenging to measure experimentally. We focus on the topical case of a

As with any quantum computing platform, semiconductor quantum dot devices

require sophisticated hardware and controls for operation. The increasing

complexity of quantum dot devices necessitates the advancement of automated

control software and image recognition techniques for rapidly evaluating charge

stability diagrams. We use an image analysis toolbox developed in Python to

automate the calibration of virtual gates, a process that previously involved a

large amount of user intervention. Moreover, we show that straightforward

We propose a practical protocol to generate and observe a non-Abelian

geometric phase using a periodically driven Raman process in the hyperfne

ground state manifold of atoms in a dilute ultracold gas. Our analysis is based

upon recent developments and application of Floquet theory to periodically

driven quantum systems. The simulation results show the non-Abelian gauge

transformation and the non-commuting property of the SU(2) transformation

operators. Based on these results, we propose a possible experimental