We present a $2\mathrm{-dimensional}$ quantum walker on curved discrete
surfaces with dynamical geometry. This walker extends the quantum walker over
the fixed triangular lattice introduced in
\cite{quantum_walk_triangular_lattice}. We write the discrete equations of the
walker on an arbitrary triangulation, whose flat spacetime limit recovers the
Dirac equation in (2+1)-dimension. The geometry is changed through Pachner
moves, allowing the surface to transform into any topologically equivalent

Universal properties of a critical quantum spin chain are encoded in the
underlying conformal field theory (CFT). This underlying CFT is fully
characterized by its conformal data. We propose a method to extract the
conformal data from a critical quantum spin chain with both periodic and
anti-periodic boundary conditions (PBC and APBC) based on low-energy
eigenstates, generalizing previous work on spin chains with only PBC. First,
scaling dimensions and conformal spins are extracted from the energies and

We introduce quantum circuits in two and three spatial dimensions which are
classically simulable, despite producing a high degree of operator
entanglement. We provide a partial characterization of these "automaton"
quantum circuits, and use them to study operator growth, information spreading,
and local charge relaxation in quantum dynamics with subsystem symmetries,
which we define as overlapping symmetries that act on lower-dimensional
submanifolds. With these symmetries, we discover the anomalous subdiffusion of

A powerful tool for studying the behavior of classical field theories is
Derrick's theorem: one may rule out the existence of localized inhomogeneous
stable field configurations (solitons) by inspecting the Hamiltonian and making
scaling arguments. For example, the theorem can be used to rule out compact
domain wall configurations for the classic $\phi^4$ theory in $3+1$ dimensions
and greater. We argue no such obstruction to constructing solitons exists in

One of the stunning consequences of quantum correlations in thermodynamics is
the reversal of the arrow of time, recently shown experimentally in [K.
Micadei, et al., Nat. Commun. 10:2456 (2019)], and manifesting itself by a
reversal of the heat flow (from the cold system to the hot one). Here, we show
that contrary to what could have been expected, heat flow reversal can happen
without reversal of the arrow of time. Moreover, contrasting with previous

We investigate the computational hardness of spin-glass instances on a square
lattice, generated via a recently introduced tunable and scalable approach for
planting solutions. The method relies on partitioning the problem graph into
edge-disjoint subgraphs, and planting frustrated, elementary subproblems that
share a common local ground state, which guarantees that the ground state of
the entire problem is known a priori. Using population annealing Monte Carlo,

We investigate the patterns in distributions of localizable entanglement over
a pair of qubits for random multi-qubit pure states. We observe that the mean
of localizable entanglement increases gradually with increasing the number of
qubits of random pure states while the standard deviation of the distribution
decreases. The effects on the distributions, when the random pure multi-qubit
states are subjected to local as well as global noisy channels, are also
investigated. Unlike the noiseless scenario, the average value of the

Number state filtered coherent states are a class of nonclassical states
obtained by removing one or more number states from a coherent state. Phase
sensitivity of an interferometer is enhanced if these nonclassical states are
used as input states. The optimal phase sensitivity, which is related to the
quantum Cramer-Rao bound (QCRB) for the input state, improves beyond the
standard quantum limit. It is argued that removal of more than one suitable
number state leads to better phase sensitivity. As an important limiting case

The so-called stellar formalism allows to represent the non-Gaussian
properties of single-mode quantum states by the distribution of the zeros of
their Husimi Q-function in phase-space. We use this representation in order to
derive an infinite hierarchy of single-mode states based on the number of zeros
of the Husimi Q-function, the stellar hierarchy. We give an operational
characterisation of the states in this hierarchy with the minimal number of
single-photon additions needed to engineer them, and derive equivalence classes

The L\"uders rule provides a way to define a quantum channel given a quantum
measurement. Using this construction, we establish an if-and-only-if condition
for the existence of a $d$-dimensional Symmetric Informationally Complete
quantum measurement (a SIC) in terms of a particular depolarizing channel.
Moreover, the channel in question satisfies two entropic optimality criteria.