# All

## Collective operations can extremely reduce work fluctuations. (arXiv:1810.02237v3 [quant-ph] UPDATED)

We consider work extraction from $N$ copies of a quantum system. When the
same work-extraction process is implemented on each copy, the relative size of
fluctuations is expected to decay as $1/\sqrt{N}$. Here, we consider protocols
where the copies can be processed collectively, and show that in this case work
fluctuations can disappear exponentially fast in $N$. As a consequence, a
considerable proportion of the average extractable work $\mathcal{W}$ can be

## Entanglement Bounds on the Performance of Quantum Computing Architectures. (arXiv:1908.04802v1 [quant-ph])

There are many possible architectures for future quantum computers that
designers will need to choose between. However, the process of evaluating a
particular connectivity graph's performance as a quantum architecture can be
difficult. In this paper, we establish a connection between a quantity known as
the isoperimetric number and a lower bound on the time required to create
highly entangled states. The metric we propose counts resources based on the
use of two-qubit unitary operations, while allowing for arbitrarily fast

## Quantum Coherence Witness with Untrusted Measurement Devices. (arXiv:1908.05022v1 [quant-ph])

Coherence is a fundamental resource in quantum information processing, which
can be certified by a coherence witness. Due to the imperfection of measurement
devices, a conventional coherence witness may lead to fallacious results. We
show that the conventional witness could mistake an incoherent state as a state
with coherence due to the inaccurate settings of measurement bases. In order to
make the witness result reliable, we propose a measurement-device-independent

## Theory of quantum oscillations in quasicrystals: Quantizing spiral Fermi surfaces. (arXiv:1811.03652v2 [cond-mat.mes-hall] UPDATED)

We show that electronic materials with disallowed rotational symmetries that
enforce quasiperiodic order can exhibit quantum oscillations and that these are
generically associated with exotic "spiral Fermi surfaces." These Fermi
surfaces are self-intersecting, and characterized by a winding number of their
surface tangent---a topological invariant---that is larger than one. We compute
the nature of the quantum oscillations in two experimentally relevant settings
which give rise to spiral Fermi surfaces: a "nearly-free-electron"

## Thermodynamic uncertainty relations from exchange fluctuation theorems. (arXiv:1904.07574v2 [quant-ph] UPDATED)

Thermodynamic uncertainty relations (TURs) place strict bounds on the
fluctuations of thermodynamic quantities in terms of the associated entropy
production. In this work we identify the tightest (and saturable) matrix-valued
TUR that can be derived from the exchange fluctuation theorems describing the
statistics of heat and particle flow between multiple systems. Our result holds
for both quantum and classical systems, undergoing general non-Markovian and
non-stationary processes. Moreover, it provides bounds not only for the

## Self-Assembled Room Temperature Multiferroic BiFeO3-LiFe5O8 Nanocomposites. (arXiv:1908.04825v1 [cond-mat.mtrl-sci])

Multiferroic materials have driven significant research interest due to their
promising technological potential. Developing new room-temperature
multiferroics and understanding their fundamental properties are important to
reveal unanticipated physical phenomena and potential applications. Here, a new
room temperature multiferroic nanocomposite comprised of an ordered
ferrimagnetic spinel LiFe5O8 (LFO) and a ferroelectric perovskite BiFeO3 (BFO)
is presented. We observed that lithium (Li)-doping in BFO favors the formation

## Graph States as a Resource for Quantum Metrology. (arXiv:1908.05047v1 [quant-ph])

By using highly entangled states, quantum metrology guarantees precision
impossible with classical measurements. Unfortunately such states can be very
susceptible to noise, and it is a great challenge of the field to maintain
quantum advantage in realistic conditions. In this study we investigate the
practicality of graph states for quantum metrology. Graph states are a natural
resource for much of quantum information, and here we characterize their
quantum Fisher information (QFI) for an arbitrary graph state. We then

## Quantum entanglement driven by electron-vibrational mode coupling. (arXiv:1804.01123v2 [cond-mat.mes-hall] UPDATED)

In this work, we provided a proof-of-principle of efficient production of
maximally entangled states using charged quantum dots coupled to vibrational
modes. The physical system consists of two pairs of quantum dots, each pair
with a single electron able to tunnel between the dots, thus encoding a qubit.
The electrons, initially not coupled, interact with two bosonic vibrational
modes. It is demonstrated that the electron-vibrational mode coupling drives to

## Scrambled Mean Field Approach to the Quantum Dynamics of Degenerate Bose Gases. (arXiv:1908.04831v1 [cond-mat.quant-gas])

We present a novel approach to modeling dynamics of trapped, degenerate,
weakly interacting Bose gases beyond the mean field limit. We transform a
many-body problem to the interaction representation with respect to a suitably
chosen part of the Hamiltonian and only then apply a multimode coherent-state
ansatz. The obtained equations are almost as simple as the Gross--Pitaevskii
equation, but our approach captures essential features of the quantum dynamics
such as the collapse of coherence.

## Strong unitary uncertainty relations. (arXiv:1908.05053v1 [quant-ph])

In this paper we provide a new set of uncertainty principles for unitary
operators using a sequence of inequalities with the help of the
geometric-arithmetic mean inequality. As these inequalities are "fine-grained"
compared with the well-known Cauchy-Schwarz inequality, our framework naturally
improves the results based on the latter. As such, the unitary uncertainty
relations based on our method outperform the best known bound introduced in
[Phys. Rev. Lett. 120, 230402 (2018)] to some extent. Explicit examples of