Quantum Preprints

The problem of objectivity, i.e. how to explain on quantum grounds the objective character of the macroscopic world, is one of the aspects of the celebrated quantum-to-classical transition. Initiated by W. H. Zurek and collaborators, this problem gained some attention recently with several approaches being developed. The aim of this... Read more
Published on: 2020-07-09
We study the harvesting of correlations by two Unruh-DeWitt static detectors from the vacuum state of a massless scalar field in background Vaidya spacetime, and we compare the results with those associated with the three preferred vacua (Boulware, Unruh, Hartle-Hawking-Israel vacua) in Schwarzschild spacetime. To do this we make use... Read more
Published on: 2020-07-09
In this paper, we consider N-level quantum angular momentum systems interacting with electromagnetic fields undergoing continuous-time measurements. We suppose unawareness of the initial state and physical parameters, entailing the introduction of an additional state representing the estimated quantum state. The evolution of the quantum state and its estimation is described... Read more
Published on: 2020-07-09
We report on the precise integration of nm-scale topological insulator Josephson junctions into mm-scale superconducting quantum circuits via selective area epitaxy and local stencil lithography. By studying dielectric losses of superconducting microwave resonators fabricated on top of our selective area growth mask, we verify the compatibility of this in situ... Read more
Published on: 2020-07-09
The main goal of this paper is to obtain the exact quantum solutions for charge space in a superconductor with time-dependent parameters using the London approach. We introduce a new quantization scheme for the charge inside a superconductor based on the Lewis and Riesenfeld invariant operator method. From the wave-functions... Read more
Published on: 2020-07-09
Instruction scheduling is a key compiler optimization in quantum computing, just as it is for classical computing. Current schedulers optimize for data parallelism by allowing simultaneous execution of instructions, as long as their qubits do not overlap. However, on many quantum hardware platforms, instructions on overlapping qubits can be executed... Read more
Published on: 2020-07-09
The celebrated exchange fluctuation theorem -- proposed by Jarzynski and Wozcik, (Phys Rev. Lett. 92, 230602 (2004)) for heat exchange between two systems in thermal equilibrium at different temperatures -- is explored here for quantum Gaussian states in thermal equilibrium. Our approach has close resemblance with the classcial phase-space trajectory... Read more
Published on: 2020-07-09
Probing extended polyene systems with energy in excess of the bright state ($1^1B_u^+$/$S_2$) band edge generates triplets via singlet fission. This process is not thought to involve the $2^1A_g^-$/$S_1$ state, suggesting that other states play a role. Using density matrix renormalisation group (DMRG) calculations of the Pariser-Parr-Pople-Peierls Hamiltonian, we investigate... Read more
Published on: 2020-07-09
In recent years, the modeling interest has increased significantly from the molecular level to the atomic and quantum scale. The field of computational chemistry plays a significant role in designing computational models for the operation and simulation of systems ranging from atoms and molecules to industrial-scale processes. It is influenced... Read more
Published on: 2020-07-09
We analyze the stabilizability of entangled two-mode Gaussian states in three benchmark dissipative models: local damping, dissipators engineered to preserve two-mode squeezed states, and cascaded oscillators. In the first two models, we determine principal upper bounds on the stabilizable entanglement, while in the last model, arbitrary amounts of entanglement can... Read more
Published on: 2020-07-09
The idea of self-testing is to render guarantees concerning the inner workings of a device based on the measurement statistics. It is one of the most formidable quantum certification and benchmarking schemes. Here, we have shown that any bipartite pure entangled state can be self-tested through Quantum Steering. Analogous to... Read more
Published on: 2020-07-09
Recent experiments involving the interaction of optical vortices with atoms in quadrupole transitions have been shown to be accompanied by the exchange of orbital angular momentum (OAM) between the electronic states of the atom and the optical vortex field. Earlier work by both theory and experiment had ruled out the... Read more
Published on: 2020-07-09
In this paper, we try to develop a theory for non-Hermitian Majorana zero modes. The universal features of non-Hermitian Majorana zero modes are obtained and we found that the non-Abelian statistics for them becomes anomalous that is different from the usual non-Abelian statistics. With the help of braiding the two... Read more
Published on: 2020-07-09
Semiconductor quantum-dot spin qubits are a promising platform for quantum computation, because they are scalable and possess long coherence times. In order to realize this full potential, however, high-fidelity information transfer mechanisms are required for quantum error correction and efficient algorithms. In this work, we demonstrate adiabatic quantum-state transfer in... Read more
Published on: 2020-07-09
In this paper we will demonstrate that any compact quantum group can be used as symmetry groups for quantum channels, which leads us to the concept of covariant channels. We, then, unearth the structure of the convex set of covariant channels by identifying all extreme points under the assumption of... Read more
Published on: 2020-07-09
We present a framework for modeling words, phrases, and longer expressions in a natural language using reduced density operators. We show these operators capture something of the meaning of these expressions and, under the Loewner order on positive semidefinite operators, preserve both a simple form of entailment and the relevant... Read more
Published on: 2020-07-09
The landmark 1982 paper of Perdew, Parr, Levy, and Balduz (often called PPLB) laid the foundation for our modern understanding of the role of the derivative discontinuity in density functional theory, which drives much development to account for its effects. A simple model for the chemical potential at vanishing temperature... Read more
Published on: 2020-07-09
We investigate the non-Langevin relative of the L'{e}vy-driven Langevin random system, under an assumption that both systems share a common (asymptotic, stationary, steady-state) target pdf. The relaxation to equilibrium in the fractional Langevin-Fokker-Planck scenario results from an impact of confining conservative force fields on the random motion. A non-Langevin alternative... Read more
Published on: 2020-07-09
Unlike their Hermitian counterparts, non-Hermitian (NH) systems may display an exponential sensitivity to boundary conditions and an extensive number of edge-localized states in systems with open boundaries, a phenomena dubbed the "non-Hermitian skin effect." The NH skin effect is one of the primary challenges to defining a topological theory of... Read more
Published on: 2020-07-09
We introduce a quantification of three-party coherence of a classical paraxial optical beam. The traditional basis-independent optical quantity called degree of polarization is determined to be the desired quantitative two-party coherence measure when appropriately generalized. A set of fundamental constraint relations is derived among three principal beam two-party coherences. The... Read more
Published on: 2020-07-09