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

# All

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

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

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 (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

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

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

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

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.

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