1,164 research outputs found
Analytic Solution for the Ground State Energy of the Extensive Many-Body Problem
A closed form expression for the ground state energy density of the general
extensive many-body problem is given in terms of the Lanczos tri-diagonal form
of the Hamiltonian. Given the general expressions of the diagonal and
off-diagonal elements of the Hamiltonian Lanczos matrix, and
, asymptotic forms and can be defined in
terms of a new parameter ( is the Lanczos iteration and is
the size of the system). By application of theorems on the zeros of orthogonal
polynomials we find the ground-state energy density in the bulk limit to be
given in general by .Comment: 10 pages REVTex3.0, 3 PS figure
Analysis and Geometric Optimization of Single Electron Transistors for Read-Out in Solid-State Quantum Computing
The single electron transistor (SET) offers unparalled opportunities as a
nano-scale electrometer, capable of measuring sub-electron charge variations.
SETs have been proposed for read-out schema in solid-state quantum computing
where quantum information processing outcomes depend on the location of a
single electron on nearby quantum dots. In this paper we investigate various
geometries of a SET in order to maximize the device's sensitivity to charge
transfer between quantum dots. Through the use of finite element modeling we
model the materials and geometries of an Al/Al2O3 SET measuring the state of
quantum dots in the Si substrate beneath. The investigation is motivated by the
quest to build a scalable quantum computer, though the methodology used is
primarily that of circuit theory. As such we provide useful techniques for any
electronic device operating at the classical/quantum interface.Comment: 13 pages, 17 figure
1A. Thyroid hormone receptors in GtoPdb v.2023.1
Thyroid hormone receptors (TRs, nomenclature as agreed by the NC-IUPHAR Subcommittee on Nuclear Hormone Receptors [12, 2]) are nuclear hormone receptors of the NR1A family, with diverse roles regulating macronutrient metabolism, cognition and cardiovascular homeostasis. TRs are activated by thyroxine (T4) and thyroid hormone (triiodothyronine). Once activated by a ligand, the receptor acts as a transcription factor either as a monomer, homodimer or heterodimer with members of the retinoid X receptor family. NH-3 has been described as an antagonist at TRs with modest selectivity for TRβ [42]
1A. Thyroid hormone receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database
Thyroid hormone receptors (TRs, nomenclature as agreed by the NC-IUPHAR Subcommittee on Nuclear Hormone Receptors [10]) are nuclear hormone receptors of the NR1A family, with diverse roles regulating macronutrient metabolism, cognition and cardiovascular homeostasis. TRs are activated by thyroxine (T4) and thyroid hormone (triiodothyronine). Once activated by a ligand, the receptor acts as a transcription factor either as a monomer, homodimer or heterodimer with members of the retinoid X receptor family. NH-3 has been described as an antagonist at TRs with modest selectivity for TRβ [38]
Matterwave Transport Without Transit
Classically it is impossible to have transport without transit, i.e., if the
points one, two and three lie sequentially along a path then an object moving
from one to three must, at some point in time, be located at two. However, for
a quantum particle in a three-well system it is possible to transport the
particle between wells one and three such that the probability of finding it at
any time in the classically accessible state in well two is negligible. We
consider theoretically the analogous scenario for a Bose-Einstein condensate
confined within a three well system. In particular, we predict the adiabatic
transportation of an interacting Bose-Einstein condensate of 2000 Li atoms from
well one to well three without transiting the allowed intermediate region. To
an observer of this macroscopic quantum effect it would appear that, over a
timescale of the order of one second, the condensate had transported, but not
transited, a macroscopic distance of 20 microns between wells one and three.Comment: 6 pages, 4 figure
Modal expansions and non-perturbative quantum field theory in Minkowski space
We introduce a spectral approach to non-perturbative field theory within the
periodic field formalism. As an example we calculate the real and imaginary
parts of the propagator in 1+1 dimensional phi^4 theory, identifying both
one-particle and multi-particle contributions. We discuss the computational
limits of existing diagonalization algorithms and suggest new quasi-sparse
eigenvector methods to handle very large Fock spaces and higher dimensional
field theories.Comment: new material added, 12 pages, 6 figure
Engineered valley-orbit splittings in quantum confined nanostructures in silicon
An important challenge in silicon quantum electronics in the few electron
regime is the potentially small energy gap between the ground and excited
orbital states in 3D quantum confined nanostructures due to the multiple valley
degeneracies of the conduction band present in silicon. Understanding the
"valley-orbit" (VO) gap is essential for silicon qubits, as a large VO gap
prevents leakage of the qubit states into a higher dimensional Hilbert space.
The VO gap varies considerably depending on quantum confinement, and can be
engineered by external electric fields. In this work we investigate VO
splitting experimentally and theoretically in a range of confinement regimes.
We report measurements of the VO splitting in silicon quantum dot and donor
devices through excited state transport spectroscopy. These results are
underpinned by large-scale atomistic tight-binding calculations involving over
1 million atoms to compute VO splittings as functions of electric fields, donor
depths, and surface disorder. The results provide a comprehensive picture of
the range of VO splittings that can be achieved through quantum engineering.Comment: 4 pages, 4 figure
Lifetime enhanced transport in silicon due to spin and valley blockade
We report the observation of Lifetime Enhanced Transport (LET) based on
perpendicular valleys in silicon by transport spectroscopy measurements of a
two-electron system in a silicon transistor. The LET is manifested as a
peculiar current step in the stability diagram due to a forbidden transition
between an excited state and any of the lower energy states due perpendicular
valley (and spin) configurations, offering an additional current path. By
employing a detailed temperature dependence study in combination with a rate
equation model, we estimate the lifetime of this particular state to exceed 48
ns. The two-electron spin-valley configurations of all relevant confined
quantum states in our device were obtained by a large-scale atomistic
tight-binding simulation. The LET acts as a signature of the complicated valley
physics in silicon; a feature that becomes increasingly important in silicon
quantum devices.Comment: 4 pages, 4 figures. (The current version (v3) is the result of
splitting up the previous version (v2), and has been completely rewritten
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