共查询到20条相似文献,搜索用时 15 毫秒
1.
Kazuki Hasebe 《Physics letters. A》2008,372(9):1516-1520
Based on the recently proposed SUSY quantum Hall effect, we show that Laughlin and Moore-Read states are related by a hidden SUSY transformation. Regarding the SUSY Laughlin wavefunction as a master wavefunction, Laughlin and Moore-Read states appear as two extreme limits of component wavefunctions. Realizations of topological excitations on Laughlin and Moore-Read states are also discussed in the SUSY formalism. We develop a stereographically projected formulation of the SUSY quantum Hall effect. With appropriate interpretation of Grassmann odd coordinates, we illustrate striking analogies between SUSY quantum Hall effect and superfluidity. 相似文献
2.
The elementary excitations of fractional quantum Hall (FQH) fluids are vortices with fractional statistics. Yet, this fundamental prediction has remained an open experimental challenge. Here we show that the cross-current noise in a three-terminal tunneling experiment of a two dimensional electron gas in the FQH regime can be used to detect directly the statistical angle of the excitations of these topological quantum fluids. We show that the noise also reveals signatures of exclusion statistics and of fractional charge. The vortices of Laughlin states should exhibit a bunching effect, while for higher states in the Jain sequences they should exhibit an "antibunching" effect. 相似文献
3.
Chyh-Hong Chern 《Annals of Physics》2007,322(10):2485-2492
We propose a pseudo-potential Hamiltonian for the Zhang-Hu’s generalized fractional quantum Hall states to be the exact and unique ground states. Analogously to Laughlin’s quasi-hole (quasi-particle), the excitations in the generalized fractional quantum Hall states are extended objects. They are vortex-like excitations with fractional charges +(−)1/m3 in the total configuration space CP3. The density correlation function of the Zhang-Hu states indicates that they are incompressible liquid. 相似文献
4.
Lukasz Fidkowski Michael Freedman Chetan Nayak Kevin Walker Zhenghan Wang 《Communications in Mathematical Physics》2009,287(3):805-827
We discuss Hilbert spaces spanned by the set of string nets, i.e. trivalent graphs, on a lattice. We suggest some routes by
which such a Hilbert space could be the low-energy subspace of a model of quantum spins on a lattice with short-ranged interactions.
We then explain conditions which a Hamiltonian acting on this string net Hilbert space must satisfy in order for the system
to be in the DFib (Doubled Fibonacci) topological phase, that is, be described at low energy by an SO(3)3 × SO(3)3 doubled Chern-Simons theory, with the appropriate non-abelian statistics governing the braiding of the low-lying quasiparticle
excitations (nonabelions). Using the string net wavefunction, we describe the properties of this phase. Our discussion is
informed by mappings of string net wavefunctions to the chromatic polynomial and the Potts model. 相似文献
5.
《Journal of Physics and Chemistry of Solids》2002,63(6-8):1289-1296
Integer and fractional quantum Hall (QH) effects are studied in bilayer electron systems both theoretically and experimentally, especially, at ν=2 and 2/3. Due to the spin and layer degrees of freedom, the SU(4) symmetry underlies the integer QH states, where quantum coherence develops spontaneously and quasiparticles are coherent excitations. It is intriguing that a pair of skyrmions makes one quasiparticle at ν=2. In the fractional QH regime, on the other hand, the composite-fermion cyclotron gap competes with the Zeeman and tunneling gaps, bringing in new phases and excitations. At ν=2/3 our experimental data suggest that a quasiparticle is not a coherent excitation but simply a composite fermion. 相似文献
6.
We demonstrate the experimental feasibility of incompressible fractional quantum Hall-like states in ultracold two-dimensional rapidly rotating dipolar Fermi gases. In particular, we argue that the state of the system at filling fraction nu = 1/3 is well described by the Laughlin wave function and find a substantial energy gap in the quasiparticle excitation spectrum. Dipolar gases, therefore, appear as natural candidates of systems that allow us to realize these very interesting highly correlated states in future experiments. 相似文献
7.
Ying-Hai Wu 《中国物理 B》2022,31(3):37302-037302
Non-Abelian anyons can emerge as fractionalized excitations in two-dimensional systems with topological order. One important example is the Moore—Read fractional quantum Hall state. Its quasihole states are zero-energy eigenstates of a parent Hamiltonian, but its quasiparticle states are not. Both of them can be modeled on an equal footing using the bipartite composite fermion method. We study the entanglement spectrum of the cases with two or four non-Abelian anyons. The counting of levels in the entanglement spectrum can be understood using the edge theory of the Moore—Read state, which reflects the topological order of the system. It is shown that the fusion results of two non-Abelian anyons is determined by their distributions in the bipartite construction. 相似文献
8.
W. Ihra M. Leadbeater J.L. Vega K. Richter 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(3):425-435
We study the effect on the density of states in mesoscopic ballistic billiards to which a superconducting lead is attached.
The expression for the density of states is derived in the semiclassical S-matrix formalism shedding light onto the origin of the differences between the semiclassical theory and the corresponding
result derived from random matrix models. Applications to a square billiard geometry and billiards with boundary roughness
are discussed. The saturation of the quasiparticle excitation spectrum is related to the classical dynamics of the billiard.
The influence of weak magnetic fields on the proximity effect in rough Andreev billiards is discussed and an analytical formula
is derived. The semiclassical theory provides an interpretation for the suppression of the proximity effect in the presence
of magnetic fields as a coherence effect of time reversed trajectories. It is shown to be in good agreement with quantum mechanical
calculations.
Received 21 August 1999 and Received in final form 21 March 2001 相似文献
9.
J.G. Hirsch P.O. Hess O. Civitarese 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):355-364
Coherent states are used as trial states to determine, variationally, the structure of the eigenvectors belonging to a schematic
Hamiltonian consisting of single-particle, pairing and residual proton-neutron interaction terms. It is shown that the standard
proton-neutron quasiparticle random-phase approximation (pn-QRPA) is recovered, as a variational theory, by replacing quasiparticle pair creation and annihilation operators by bosons.
It is also shown that an exact, algebra preserving, mapping of the Hamiltonian is needed to describe the spectrum beyond the
QRPA phase transition. The role of the spurious components of the trial wave functions is discussed.
Received: 19 February 2002 / Accepted: 3 May 2002 相似文献
10.
H. Niggemann J. Zittartz 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(4):731-738
We present a class of optimum ground states for quantum spin- models on the Cayley tree with coordination number 3. The interaction is restricted to nearest neighbours and contains 5
continuous parameters. For all values of these parameters the Hamiltonian has parity invariance, spin-flip invariance, and
rotational symmetry in the xy-plane of spin space. The global ground states are constructed in terms of a 1-parametric vertex state model, which is a direct generalization of the well-known matrix product ground state approach. By using recursion relations and the transfer matrix technique we derive exact analytical expressions for local
fluctuations and longitudinal and transversal two-point correlation functions.
Received 1 March 1999 相似文献
11.
J. Bauer A. C. Hewson 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(3):235-249
We analyze the properties of the quasiparticle excitations of metallic
antiferromagnetic states in a strongly correlated electron system. The study is based on
dynamical mean field theory (DMFT) for the infinite dimensional Hubbard model with
antiferromagnetic symmetry breaking. Self-consistent solutions of the DMFT
equations are calculated using the numerical renormalization group (NRG). The
low energy behavior in these results is then analyzed in terms
of renormalized quasiparticles. The parameters for these quasiparticles are
calculated directly from the NRG derived self-energy, and also from the low
energy fixed point of the effective impurity model. From these the quasiparticle
weight and the effective mass are deduced. We show that
the main low energy features of the k-resolved spectral density can be understood in
terms of the quasiparticle picture. We also find that Luttinger's theorem
is satisfied for the total electron number in the doped antiferromagnetic
state. 相似文献
12.
D.A. Garanin K. Kladko P. Fulde 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(2):293-300
We extend and apply a previously developed method for a semiclassical treatment of a system with large spin S. A multisite Heisenberg Hamiltonian is transformed into an effective classical Hamilton function which can be treated by
standard methods for classical systems. Quantum effects enter in form of multispin interactions in the Hamilton function. The latter is written in the form of an expansion in powers of J/(TS), where J is the coupling constant. Main ingredients of our method are spin coherent states and cumulants. Rules and diagrams are derived
for computing cumulants of groups of operators entering the Hamiltonian. The theory is illustrated by calculating the quantum
corrections to the free energy of a Heisenberg chain which were previously computed by a Wigner-Kirkwood expansion.
Received 5 May 1999 and received in final form 24 September 1999 相似文献
13.
O. Ciftja 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(4):671-677
The experimentally observed filling factors of the fractional quantum Hall effect can be described in terms of the composite
fermion wave function of the Jastrow-Slater form [0pt] fully projected into the lowest Landau level. The Slater determinant of the above composite fermion wave function represents
the filled Landau levels of composite fermions evaluated at the corresponding reduced magnetic field. For a system of fermions
studied in the thermodynamic limit, we prove that in the even-denominator-filled state limit (when the number of filled Landau
levels of composite fermions becomes infinite), the above composite fermion wave function exactly transforms into the Rezayi-Read
Fermi-sea-like wave function [0pt] constructed by attaching 2m flux quanta to the Slater determinant of two-dimensional free fermions at the density corresponding to that filling. We study
the composite fermion wave function and its evolution into the Fermi-sea-like wave function for a range of filling factors
very close to the even-denominator-filled state.
Received 19 March 1999 相似文献
14.
15.
Yu.N. Lobach A.D. Efimov A.A. Pasternak 《The European Physical Journal A - Hadrons and Nuclei》1999,6(2):131-140
Lifetimes of excited states in 110Cd have been measured by the Doppler shift attenuation method in the reaction (α,2nγ) at E
α= 25 MeV. Lifetime values for 8 states and lifetime limits for 3 states were obtained. The band structures of 110Cd have been interpreted in terms of a modified version of the interacting boson model (IBM + 2 q.p.). The calculations explain
well the excitation energies and electromagnetic transition probabilities up to J
π= 16+, except for the 10+
1 state. The structural features are discussed in terms of collective and two quasiparticle excitations.
Received: 20 March 1999 / Revised version: 28 May 1999 相似文献
16.
M. Brunner F.F. Assaad A. Muramatsu 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(2):209-212
We present a new finite-temperature quantum Monte Carlo algorithm to compute imaginary-time Green functions for a single hole
in the t-J model on non-frustrated lattices. Spectral functions are obtained with the Maximum Entropy method. Simulations of the one-dimensional
case show that a simple charge-spin separation Ansatz is able to describe the overall features of the spectral function such as the bandwidth and the compact support of the spectral function, over the whole energy range for values of J
/
t from 1/3 to 4. This is contrasted with the two-dimensional case. The quasiparticle weight Zk is computed on lattices up to L
=128 sites in one dimension, and scales as .
Received 15 February 2000 相似文献
17.
In topological quantum computation, quantum information is stored in states which are intrinsically protected from decoherence, and quantum gates are carried out by dragging particlelike excitations (quasiparticles) around one another in two space dimensions. The resulting quasiparticle trajectories define world lines in three-dimensional space-time, and the corresponding quantum gates depend only on the topology of the braids formed by these world lines. We show how to find braids that yield a universal set of quantum gates for qubits encoded using a specific kind of quasiparticle which is particularly promising for experimental realization. 相似文献
18.
P. Maurel M.B. Lepetit D. Poilblanc 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):481-484
Elementary excitations of the 4k
F charge density wave state of a quarter-filled strongly correlated electronic one-dimensional chain are investigated in the
presence of dispersionless quantum optical phonons using Density Matrix Renormalization Group techniques. Such excitations
are shown to be topological solitons carrying charge e/2 and spin zero. Relevance to the 4k
F charge density wave instability in (DI - DCNQI)2
A
g or recently discovered in (TMTTF)2X ( X=PF
6, AsF6) is discussed.
Received 30 March 2001 and Received in final form 11 May 2001 相似文献
19.
We report an Aharonov-Bohm superperiod of five magnetic flux quanta (5h/e) observed in a Laughlin quasiparticle interferometer, where an edge channel of the 1/3 fractional quantum Hall fluid encircles an island of the 2/5 fluid. This result does not violate the gauge invariance argument of the Byers-Yang theorem because the magnetic flux, in addition to affecting the Aharonov-Bohm phase of the encircling 1/3 quasiparticles, creates the 2/5 quasiparticles in the island. The superperiod is accordingly understood as imposed by the anyonic statistical interaction of Laughlin quasiparticles. 相似文献
20.
We present explicit wavefunctions for quasi-hole excitations over a variety of non-abelian quantum Hall states: the Read-Rezayi states with k ? 3 clustering properties and a paired spin-singlet quantum Hall state. Quasi-holes over these states constitute a topological quantum register, which can be addressed by braiding quasi-holes. We obtain the braid properties by direct inspection of the quasi-hole wavefunctions. We establish that the braid properties for the paired spin-singlet state are those of ‘Fibonacci anyons’, and thus suitable for universal quantum computation. Our derivations in this paper rely on explicit computations in the parafermionic conformal field theories that underly these particular quantum Hall states. 相似文献