2,852 research outputs found
Realization of Probabilistic Identification and Clone of Quantum-States II Multiparticles System
We realize the probabilistic cloning and identifying linear independent
quantum states of multi-particles system, given prior probability, with
universal quantum logic gates using the method of unitary representation. Our
result is universal for separate state and entanglement. We also provide the
realization in the condition given initial copies for each state.Comment: 18 Pages, 3 Figures, ReVTe
Conditions for manipulation of a set of entangled pure states
We derive a sufficient condition for a set of pure states, each entangled in
two remote -dimensional systems, to be transformable to
-dimensional-subspace equivalent entangled states () by same local
operations and classical communication. If , the condition is also
necessary. This condition reveals the function of the relative marginal density
operators of the entangled states in the entanglement manipulation without
sufficient information of the initial states.Comment: 5 Pages, no Figure, REVTeX. The generalization of quant-ph/990801
Protected quantum-state transfer in decoherence-free subspaces
We propose and analyse a robust quantum state transfer protocol by the use of
a combination of coherent quantum coupling and decoherence-free subspaces in a
coupled quantum spin chain. Under decoherence, an arbitrary unknown quantum
state embedded in a decoherence-free subspace can be perfectly transferred
through a noisy channel being weakly coupled to two end registers. The method
protects quantum information from both the channel noise and the environmental
decoherence. A special case of utilizing two physical qubits to encode one
logical qubit is considered as an example and the robustness is confirmed by
numerical performances
High frequency limit for single-electron pumping operations
In this Letter, we study the transient electron transfer phenomena of
single-electron devices with alternating external gate voltages. We obtain a
high frequency limit for pumping electrons one at a time in single-electron
devices. Also, we find that in general the electrical current is not
proportional to the frequency of the external signals in the single-electron
devices, due to the strong quantum coherence tunneling effect.Comment: 4 pages 5 figure
Real-time dynamics of single-electron pumping
In this Letter, we study the real-ime dynamics of single-electron pumpings.
We modulate the left tunneling barrier along with the dot level but slightly
changing the right barrier to operate the single-electron pumping device at
zero bias. We show the adiabatic to the non-adiabatic transition in pumping
operations. We also find that the relation is only valid in
the low operating frequency adiabatic regime.Comment: 4 pages, 5 figure
Molecular Computing for Markov Chains
In this paper, it is presented a methodology for implementing arbitrarily
constructed time-homogenous Markov chains with biochemical systems. Not only
discrete but also continuous-time Markov chains are allowed to be computed. By
employing chemical reaction networks (CRNs) as a programmable language,
molecular concentrations serve to denote both input and output values. One
reaction network is elaborately designed for each chain. The evolution of
species' concentrations over time well matches the transient solutions of the
target continuous-time Markov chain, while equilibrium concentrations can
indicate the steady state probabilities. Additionally, second-order Markov
chains are considered for implementation, with bimolecular reactions rather
that unary ones. An original scheme is put forward to compile unimolecular
systems to DNA strand displacement reactions for the sake of future physical
implementations. Deterministic, stochastic and DNA simulations are provided to
enhance correctness, validity and feasibility
Probabilistic representations of solutions of elliptic boundary value problem and non-symmetric semigroups
In this paper, we use a probabilistic approach to show that there exists a
unique, bounded continuous solution to the Dirichlet boundary value problem for
a general class of second order non-symmetric elliptic operators with
singular coefficients, which does not necessarily have the maximum principle.
The theory of Dirichlet forms and heat kernel estimates play a crucial role in
our approach. A probabilistic representation of the non-symmetric semigroup
generated by is also given
Universal Quantum Entanglement Concentration Gate
We construct a Universal Quantum Entanglement Concentration Gate (QEC-Gate).
Special times operations of QEC-Gate can transform a pure 2-level bipartite
entangled state to nearly maximum entanglement. The transformation can attain
any required fidelity with optimal probability by adjusting concentration step.
We also generate QEC-Gate to the Schmidt decomposable multi-partite system.Comment: 3 Pages, No Figure, REVTe
Short-term Market Reaction after Trading Halts in Chinese Stock Market
In this paper, we study the dynamics of absolute return, trading volume and
bid-ask spread after the trading halts using high-frequency data from the
Shanghai Stock Exchange. We deal with all three types of trading halts, namely
intraday halts, one-day halts and inter-day halts, of 203 stocks in Shanghai
Stock Exchange from August 2009 to August 2011. We find that absolute return,
trading volume, and in case of bid-ask spread around intraday halts share the
same pattern with a sharp peak and a power law relaxation after that. While for
different types of trading halts, the peaks' height and the relaxation
exponents are different. From the perspective of halt reasons or halt duration,
the relaxation exponents of absolute return after inter-day halts are larger
than that after intraday halts and one-day halts, which implies that inter-day
halts are most effective. From the perspective of price trends, the relaxation
exponents of excess absolute return and excess volume for positive events are
larger than that for negative events in case of intraday halts and one-day
halts, implying that positive events are more effective than negative events
for intraday halts and one-day halts. In contrast, negative events are more
effective than positive events for inter-day halts.Comment: 11 pages, 8 figures, Physica A (2014
Master equation approach to transient quantum transport incorporating with initial correlations
In this paper, the exact transient quantum transport of non-interacting
nanostructures is investigated in the presence of initial system-lead
correlations and initial lead-lead correlations for a device system coupled to
general electronic leads. The exact master equation incorporating with initial
correlations is derived through the extended quantum Langevin equation. The
effects of the initial correlations are manifested through the time-dependent
fluctuations contained explicitly in the exact master equation. The transient
transport current incorporating with initial correlations is obtained from the
exact master equation. The resulting transient transport current can be
expressed in terms of the single-particle propagating and correlation Green
functions of the device system. We show that the initial correlations can
affect quantum transport not only in the transient regime, but also in the
steady-state limit when system-lead couplings are strong enough so that
electron localized bound states occur in the device system.Comment: 13pages, 4figure
- …