# All

## Sensing electrons during an adiabatic coherent transport passage. (arXiv:1901.10057v1 [cond-mat.mes-hall])

We study the detection of electrons undergoing coherent transfer via
adiabatic passage (CTAP) in a triple quantum-dot system with a quantum
point-contact sensing the change of the middle dot. In the ideal scenario, the
protocol amounts to perfect change transfer between the external dots with
vanishing occupation of the central dot at all times, rendering the measurement
and its backaction moot. Nevertheless, even with minor corrections to the
protocol, a small population builds up in the central dot. We study the

## Floquet dynamical quantum phase transitions. (arXiv:1901.10365v1 [quant-ph])

Dynamical quantum phase transitions (DQPTs) are manifested by time-domain
nonanalytic behaviors of many-body systems.Introducing a quench is so far
understood as a typical scenario to induce DQPTs.In this work, we discover a
novel type of DQPTs, termed "Floquet DQPTs", as intrinsic features of systems
with periodic time modulation.Floquet DQPTs occur within each period of
continuous driving, without the need for any quenches.In particular, in a
harmonically driven spin chain model, we find analytically the existence of

## Characterizing the multipartite continuous-variable entanglement structure from squeezing coefficients and the Fisher information. (arXiv:1804.08296v2 [quant-ph] UPDATED)

Understanding the distribution of quantum entanglement over many parties is a
fundamental challenge of quantum physics and is of practical relevance for
several applications in the field of quantum information. Here we use methods
from quantum metrology to microscopically characterize the entanglement
structure of multimode continuous-variable states in all possible
multi-partitions and in all reduced distributions. From experimentally measured
covariance matrices of Gaussian states with 2, 3, and 4 photonic modes with

## Stabilization and manipulation of multispin states in quantum-dot time crystals with Heisenberg interactions. (arXiv:1810.05781v2 [quant-ph] UPDATED)

A discrete time crystal is a recently discovered non-equilibrium phase of
matter that has been shown to exist in disordered, periodically driven Ising
spin chains. In this phase, if the system is initially prepared in one of a
certain class of pure multispin product states, it periodically returns to this
state over very long time scales despite the presence of interactions,
disorder, and pulse imperfections. Here, we show that this phase occurs in GaAs

## Subspace Stabilization Analysis for Non-Markovian Open Quantum Systems. (arXiv:1901.10088v1 [quant-ph])

Hamiltonian H, coupling operator L, and memory kernel function {\gamma}, which
is a proper candidate for describing the dynamics of various solid-state
quantum information processing devices. We look into the subspace stabilization
problem of the system from the perspective of dynamical systems and control.
The problem translates itself into finding analytic conditions that
characterize invariant and attractive subspaces. Necessary and sufficient

## Selective Hybrid Spin Interactions with Low Radiation Power. (arXiv:1901.10366v1 [quant-ph])

We present a protocol for designing appropriately extended $\pi$ pulses that
achieves tunable, thus selective, electron-nuclear spin interactions with
low-driving radiation power. Our method is general since it can be applied to
different quantum sensor devices such as nitrogen vacancy centers or silicon
vacancy centers. Furthermore, it can be directly incorporated in commonly used
stroboscopic dynamical decoupling techniques to achieve enhanced nuclear
selectivity and control, which demonstrates its flexibility.

## Nonclassicality as a Quantifiable Resource for Quantum Metrology. (arXiv:1804.09355v2 [quant-ph] UPDATED)

We establish the nonclassicality of continuous-variable states as a resource
for quantum metrology. Based on the quantum Fisher information of multimode
quadratures, we introduce the metrological power as a measure of
nonclassicality with a concrete operational meaning of displacement sensitivity
beyond the classical limit. This measure belongs to the resource theory of
nonclassicality, which is nonincreasing under linear optical elements. Our
Letter reveals that a single copy, highly nonclassical quantum state is

## Versatile laser-free trapped-ion entangling gates. (arXiv:1810.08300v2 [quant-ph] UPDATED)

We present a general theory for laser-free entangling gates with trapped-ion
hyperfine qubits, using either static or oscillating magnetic-field gradients
combined with a pair of uniform microwave fields symmetrically detuned about
the qubit frequency. By transforming into a `bichromatic' interaction picture,
we show that either ${\hat{\sigma}_{\phi}\otimes\hat{\sigma}_{\phi}}$ or
${\hat{\sigma}_{z}\otimes\hat{\sigma}_{z}}$ geometric phase gates can be
performed. The gate basis is determined by selecting the microwave detuning.

## Monitoring Spontaneous Charge-density Fluctuations by Single-molecule Diffraction of Quantum Light. (arXiv:1901.10093v1 [physics.chem-ph])

Homodyne X-ray diffraction signals produced by classical light and classical
detectors are given by the modulus square of the charge density in momentum
space $\left|\sigma(\mathbf{q})\right|^{2}$, missing its phase which is
required in order to invert the signal to real space. We show that quantum
detection of the radiation field yields a linear diffraction pattern that
reveals $\sigma(\mathbf{q})$ itself, including the phase. We further show that
repeated diffraction measurements with variable delays constitute a novel

## Construction of Many-Body Eigenstates with Displacement Transformations. (arXiv:1901.10368v1 [quant-ph])

Many-body eigenstates beyond the gaussian approximation can be constructed in
terms of local integrals of motion (IOM), although their actual computation has
been until now a daunting task. We present a new practical computation of IOMS
based on displacement transformations. It represents a general and systematic
way to extend Hartree-Fock and configuration interaction theories to higher
order. Our method combines minimization of energy and energy variance of a