6,535 research outputs found
Breakdown of local convertibility through Majorana modes in a quantum quench
The local convertibility of quantum states, measured by the R\'enyi entropy,
is concerned with whether or not a state can be transformed into another state,
using only local operations and classical communications. We found that in the
one-dimensional Kitaev chain with quenched chemical potential , the
convertibility between the state for and that for ,
depends on the quantum phases of the system ( is a perturbation).
This is similar to the adiabatic case where the ground state is considered.
Specifically, when the quenched system has edge modes and the subsystem size
for the partition is much larger than the correlation length of the Majorana
fermions which forms the edge modes, the quenched state is locally
inconvertible. We give a physical interpretation for the result, based on
analyzing the interactions between the two subsystems for various partitions.
Our work should help to better understand the many-body phenomena in
topological systems and also the entanglement properties in the Majorana
fermionic quantum computation.Comment: 8 pages, 5 figures, accepted by Physical Review
Extracting entangled qubits from Majorana fermions in quantum dot chains through the measurement of parity
We propose a scheme for extracting entangled charge qubits from quantum-dot
chains that support zero-energy edge modes. The edge mode is composed of
Majorana fermions localized at the ends of each chain. The qubit, logically
encoded in double quantum dots, can be manipulated through tunneling and
pairing interactions between them. The detailed form of the entangled state
depends on both the parity measurement (an even or odd number) of the
boundary-site electrons in each chain and the teleportation between the chains.
The parity measurement is realized through the dispersive coupling of
coherent-state microwave photons to the boundary sites, while the teleportation
is performed via Bell measurements. Our scheme illustrates \emph{localizable
entanglement} in a fermionic system, which serves feasibly as a quantum
repeater under realistic experimental conditions, as it allows for finite
temperature effect and is robust against disorders, decoherence and
quasi-particle poisoning.Comment: Accepted by Scientific Report
The profitability of technical analysis in the Taiwan-U.S. forward foreign exchange market
Based on technical analysis and White's and Hansen's data-snooping-robust tests, we examine the efficiency of the Taiwan-U.S. forward foreign exchange market and find that, unlike the spot market, the forward market is inefficient even under a very high transaction cost, suggesting that the failure of forward rate unbiasedness documented in the literature may be due to forward market inefficiency.data snooping, forward exchange rate unbiasedness, market efficiency, profitability, reality check, technical analysis
Intermediate-pressure phases of cerium studied by an LDA + Gutzwiller method
The thermodynamic stable phase of cerium metal in the intermediate pressure
regime (5.0--13.0 GPa) is studied in detail by the newly developed
local-density approximation (LDA)+ Gutzwiller method, which can include the
strong correlation effect among the 4\textit{f} electrons in cerium metal
properly. Our numerical results show that the phase, which has the
distorted body-centered-tetragonal structure, is the thermodynamic stable phase
in the intermediate pressure regime and all the other phases including the
phase (-U structure), phase (fcc structure), and bct
phases are either metastable or unstable. Our results are quite consistent with
the most recent experimental data.Comment: 17 pages, 7 figure
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