Gauge theories, through the local symmetry which is in their core, exhibit

many local constraints, that must be taken care of and addressed in any

calculation. In the Hamiltonian picture this is phrased through the Gauss laws,

local constraints that restrict the physical Hilbert space and relate the

matter and gauge degrees of freedom. In this work, we present a way that uses

all the Gauss laws in lattice gauge theories with staggered fermions for

completely removing the matter degrees of freedom, at the cost of locally

# All

Recent works have shown that the spectroscopic access to highly-excited

states provides enough information to characterize transition states in

isomerization reactions. Here, we show that the transition state of the bond

breaking HCN-HNC isomerization reaction can also be achieved with the

two-dimensional limit of the algebraic vibron model. We describe the system's

bending vibration with the algebraic Hamiltonian and use its classical limit to

characterize the transition state. Using either the coherent state formalism or

The accurate and reliable description of measurement devices is a central

problem in both observing uniquely non-classical behaviors and realizing

quantum technologies from powerful computing to precision metrology. To date

quantum tomography is the prevalent tool to characterize quantum detectors.

However, such a characterization relies on accurately characterized probe

states, rendering reliability of the characterization lost in circular

argument. Here we report a self-characterization method of quantum measurements

The Dirac equation with both scalar and vector couplings describing the

dynamics of a two-dimensional Dirac oscillator in the cosmic string spacetime

is considered. We derive the Dirac-Pauli equation and solve it in the limit of

the spin and the pseudo-spin symmetries. We analyze the presence of cylindrical

symmetric scalar potentials which allows us to provide analytic solutions for

the resultant field equation. By using an appropriate ansatz, we find that the

Understanding and controlling exciton transport is a strategic way to enhance

the optoelectronic properties of high-performance organic devices. In this

article we study triplet exciton migration in crystalline poly($p$-phenylene

vinylene) polymer (PPV) using comprehensive electronic structure and quantum

dynamical methods. We solve the coupled electron-nuclear dynamics for the

triplet energy migrating between two neighboring Frenkel sites in J- and

H-aggregate arrangements. From the two-site model we extract key parameters for

We propose a scheme for entangling the motion of two massive objects in a

hybrid electromechanical architecture. The entanglement is generated due to the

interaction of two mechanical oscillators with a mediating superconducting

qubit. We show that the generated macroscopic entangled states are non-Gaussian

and its lifetime is limited by coherence time of the qubit. The entanglement is

attainable in a wide range of parameters with appropriate control of the qubit.

.We expound an alternative to the Copenhagen interpretation of the formalism

of nonrelativistic quantum mechanics. The basic difference is that the new

interpretation is formulated in the language of epistemological realism. The

{\psi} function is no longer interpreted as a probability amplitude of the

observed behaviour of elementary particles but as an objective physical field

representing the particles themselves. The particles are thus extended objects

In a recent paper [Bardyn et al. Phys. Rev. X 8, 011035 (2018)], it was shown

that the generalization of the many-body polarization to mixed states can be

used to construct a topological invariant which is also applicable to

finite-temperature and non-equilibrium Gaussian states of lattice fermions. The

many-body polarization defines an ensemble geometric phase (EGP) which is

identical to the Zak phase of a fictitious Hamiltonian, whose symmetries

determine the topological classification. Here we show that in the case of

Both theoretical and experimental studies of topological phases in

non-Hermitian systems have made a remarkable progress in the last few years of

research. In this article, we review the key concepts pertaining to topological

phases in non-Hermitian Hamiltonians with relevant examples and realistic model

setups. Discussions are devoted to both the adaptations of topological

invariants from Hermitian to non-Hermitian systems, as well as origins of new

topological invariants in the latter setup. Unique properties such as

Recently developed parity (P) and time-reversal (T) symmetric non-Hermitian

quantum theory is envisioned to have far-reaching implications and

applications. It is known that the PT-inner product is defined with respect to

a non-canonical, system generated symmetry, namely the C symmetry. We show that

the PT symmetric equation of motion is defined by the simultaneous time

evolution of the state $\psi(t)$ and the operator C(t) to manifests unitarity -

a situation analogous to the Dirac/interaction picture. The time-dependent C