We introduce the task of anonymous metrology, in which a physical parameter
of an object may be determined without revealing the object's location. Alice
and Bob share a correlated quantum state, with which one of them probes the
object. Upon receipt of the quantum state, Charlie is then able to estimate the
parameter without knowing who possesses the object. We show that quantum
correlations are resources for this task when Alice and Bob do not trust the

Planar topological superconductors with power-law decaying pairing display
different kinds of topological phase transitions where quasiparticles dubbed
non-local massive Dirac fermions emerge. These exotic particles form through
long-range interactions between distant Majorana modes at the boundary of the
system. We show how these propagating massive Dirac fermions neither mix with
bulk states nor Anderson-localize up to large amounts of static disorder

Various inequalities (Boole inequality, Chung-Erd\"os inequality, Frechet
inequality) for Kolmogorov (classical) probabilities are considered. Quantum
counterparts of these inequalities are introduced, which have an extra `quantum
correction' term, and which hold for all quantum states. When certain
sufficient conditions are satisfied, the quantum correction term is zero, and
the classical version of these inequalities holds for all states. But in
general, the classical version of these inequalities is violated by some of the

Measurement-based quantum computation, an alternative paradigm for quantum
information processing, uses simple measurements on qubits prepared in cluster
states, a class of multiparty entangled states with useful properties. Here we
propose and analyze a scheme that takes advantage of the interplay between
spin-orbit coupling and superexchange interactions, in the presence of a
coherent drive, to deterministically generate macroscopic arrays of cluster
states in fermionic alkaline earth atoms trapped in three dimensional (3D)

Causal nonseparability refers to processes where events take place in a
coherent superposition of different causal orders. These may be the key
resource for experimental violations of causal inequalities and have been
recently identified as resources for concrete information-theoretic tasks.
Here, we take a step forward by deriving a complete operational framework for
causal nonseparability as a resource. Our first contribution is a formal
definition of quantum control of causal orders, a stronger form of causal

We investigate the quantum correlation dynamics in a dark-soliton qubits with
special attention to quantum discord. Recently, dark-soliton qubit exhibiting
appreciably long lifetime are proved to be an excellent candidate for
information processing. Depending on the precise distance between the
dark-soliton qubits, the decay rate of Dicke symmetric and antisymmetric state
is suppressed or enhanced. With the Renyi-2 entropy, we derive a simple
analytical expression for the quantum discord, and explore the generation and

Measurement-device-independent quantum key distribution (MDI-QKD) is the only
known QKD scheme that can completely overcome the problem of detection
side-channel attacks. Yet, despite its practical importance, there is no
standard approach towards proving the security of MDI-QKD. Here, we present a
simple numerical method that can efficiently compute almost-tight security
bounds for any discretely modulated MDI-QKD protocol. To demonstrate the broad
utility of our method, we use it to analyze the security of coherent-state

For quantum computing to become fault tolerant, the underlying quantum bits
must be effectively isolated from the noisy environment. It is well known that
including an electromagnetic bandgap around the qubit operating frequency
improves coherence for superconducting circuits. However, investigations of
bandgaps to other environmental coupling mechanisms remain largely unexplored.
Here we present a method to enhance the coherence of superconducting circuits

This paper argues against the proposal to draw from current research into a
physical theory of quantum gravity the ontological conclusion that spacetime or
spatiotemporal relations are not fundamental. As things stand, the status of
this proposal is like the one of all the other claims about radical changes in
ontology that were made during the development of quantum mechanics and quantum
field theory. However, none of these claims held up to scrutiny as a
consequence of the physics once the theory was established and a serious

To alleviate the computational cost associated with on-the-fly ab initio
semiclassical calculations of molecular spectra, we propose the single-Hessian
thawed Gaussian approximation, in which the Hessian of the potential energy at
all points along an anharmonic classical trajectory is approximated by a
constant value. The spectra obtained with this approximation are compared with
the exact quantum spectra of a one-dimensional Morse potential and with the
experimental spectra of ammonia and quinquethiophene. In all cases, the