[Show abstract][Hide abstract] ABSTRACT: A robust scheme for unknown entangled state transfer and C-Not gate
implemented between two spatially separated atoms is proposed. It is shown
that, in the effective three-atom Ising model, two-atom unknown entangled state
can be transferred from one pair of atoms to another deterministically by only
repeating a simple operation of turning on/off local laser field applied on
atom for two times at controlling time $\frac{\pi}{2\Omega_{0}}$. The whole
time cost is less than $\frac{3\pi}{2\Omega_{0}}$. The successful probability
and the fidelity are almost 100% for small atomic spontaneous emission rate.
Deterministic two-atom C-Not gate can also be implemented in this model by just
turning on/off the local laser field applied on the single target atom and
leaving the controlling atom in its cavity alone for a while. The whole time
cost is less than $\frac{\pi}{2\Omega_{0}}+\frac{3\pi \Delta}{2g^{2}}$. It is
demonstrated that the scheme is insensitive to cavity leakage and fiber loss.
[Show abstract][Hide abstract] ABSTRACT: A robust quantum state transfer scheme is discussed for three atoms that are
trapped by separated cavities linked via optical fibers in ring-connection. It
is shown that, under the effective three-atom Ising model, arbitrary quantum
state can be transferred from one atom to another deterministically via an
auxiliary atom with maximum unit fidelity. The only required operation for this
scheme is replicating turning on/off the local laser fields applied to the
atoms for two steps with time cost $\frac{\sqrt{2}\pi}{\Gamma_{0}}$. The scheme
is insensitive to cavity leakage and atomic position due to the condition
$\Delta \approx \kappa\gg g$. Another advantage of this scheme is that the
cooperative influence of spontaneous emission and operating time error can
reduce the time cost for maximum fidelity and thus speed up the implementation
of quantum state transfer.
Chinese Physics Letters 03/2015; 32(6). DOI:10.1088/0256-307X/32/6/060303 · 0.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The key mechanism which enables two-qubit operations of a hybrid quantum processing unit for hybrid quantum computing is demonstrated. A scheme which realizes a disguised switch for two-qubit gating is proposed, combining external magnetic field control, quantum dot sample tuning, and assisted laser control. Our methods overcome the limitation of asynchrony between single-qubit operations of respective solid-state qubits and improve the efficiency of single-qubit gating.
International Journal of Theoretical Physics 02/2014; 54(2):657-663. DOI:10.1007/s10773-014-2257-8 · 1.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose two schemes to one-step generate the three-particle Greenberger–Horne–Zeilinger state based on the resonant atom–cavity fields interaction. The whole process may be realized experimentally providing that simple apparatus, initial conditions, and some manipulation in principle are achieved. Finally, in the current or the near future experiment parameter, we show that the proposed schemes can maintain the state with high fidelity under the condition of atomic spontaneous emission and decay of cavity fields.
Journal of the Optical Society of America B 07/2012; 29(7-7):1744-1749. DOI:10.1364/JOSAB.29.001744 · 1.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We construct a novel Λ-type system via the dressed states formed by the coupling between a superconducting qubit and a transmission line resonator (TLR). Compared with the conventional three-level structure, our model averts the decay of excited states. We choose the two lowest energy dressed states as the logical states. The single qubit quantum gate can be realized by the adiabatic passage and three-step operation method, respectively. Based on realistic parameters, the feasibility of the adiabatic passage method is discussed. Also, we calculate the fidelity (0.9996) of realizing the single qubit gate with the three-step operation method.
Chinese Physics Letters 12/2011; 28(12). DOI:10.1088/0256-307X/28/12/120304 · 0.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We discuss the creation of quantum discord between two two-level atoms
trapped in an optical cavity in a noisy environment. It is shown that nonzero
steady-state quantum discord between atoms can be obtained when the white-noise
field is separately imposed on atoms or cavity mode, while the steady-state
quantum discord reaches zero if both cavity mode and atoms are driven
simultaneously by white-noise fields. In particular, we demonstrate that
white-noise field in different cases can play a variously constructive role in
the generation of quantum discord.
Journal of the Optical Society of America B 11/2011; 27(9). DOI:10.1364/JOSAB.27.001799 · 1.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose a theoretical scheme of quantum nondemolition measurement of
two-qubit Werner state. We discuss our scheme with the two qubits restricted in
a local place and then extend the scheme to the case in which two qubits are
separated. We also consider the experimental realization of our scheme based on
cavity quantum electrodynamics. It is very interesting that our scheme is
robust against the dissipative effects introduced by the probe process. We also
give a brief interpretation of our scheme finally.
Physical Review A 10/2011; 82(4). DOI:10.1103/PhysRevA.82.04211 · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We develop an architecture of hybrid quantum solid-state processing unit for
universal quantum computing. The architecture allows distant and nonidentical
solid-state qubits in distinct physical systems to interact and work
collaboratively. All the quantum computing procedures are controlled by optical
methods using classical fields and cavity QED. Our methods have prominent
advantage of the insensitivity to dissipation process benefiting from the
virtual excitation of subsystems. Moreover, the QND measurements and state
transfer for the solid-state qubits are proposed. The architecture opens
promising perspectives for implementing scalable quantum computation in a
broader sense that different solid-state systems can merge and be integrated
into one quantum processor afterwards.
Physical Review A 06/2011; 84(4). DOI:10.1103/PhysRevA.84.042339 · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We reexamine quantum correlation from the fundamental perspective of its
consanguineous quantum property, the coherence. We emphasize the importance of
specifying the tensor product structure of the total state space before
discussing quantum correlation. A measure of quantum correlation for arbitrary
dimension bipartite states using nonlocal coherence is proposed, and it can be
easily generalized to the multipartite case. The quantification of
non-entangled component within quantum correlation is investigated for certain
states.
International Journal of Theoretical Physics 11/2010; 51(11). DOI:10.1007/s10773-012-1215-6 · 1.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose a new controllable protocol for information transmission which is based on coupling superconducting charge qubits to a single-mode quantum transmission line. We show how to physically implement high-fidelity information transmission by controlling the external magnetic flux in this system. By choosing appropriate parameters, the cluster states can be generated. Finally, we investigate the feasibility of this protocol with present-day technology.
Physica Scripta 11/2010; 82(6):065010. DOI:10.1088/0031-8949/82/06/065010 · 1.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We study the dynamics of quantum coherence and quantum correlations in two
semiconductor double-dot molecules separated by a distance and indirectly
coupled via a transmission line resonator. Dominant dissipation processes are
considered. The numerical results show the sudden death of entanglement and the
robustness of quantum discord to sudden death. Furthermore, the results
indicate the dephasing processes in our model can lead in the revival and decay
of coherence and discord with the absence of entanglement for certain initial
states. By observing the dynamics of coherence versus discord for different
initial states, we find that the similarities and differences of coherence and
discord are not only related to the dependance of discord on optimizing the
measurement set, but more importantly to the coherences in individual qubits
which are captured by the adopted coherence measure.
Journal of Physics B Atomic Molecular and Optical Physics 11/2010; 44(3). DOI:10.1088/0953-4075/44/3/035501 · 1.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose a scheme to efficiently produce large cluster states by using many superconducting Josephson junction flux qubits coupling to the quantized nanomechanical resonator (NAMR). This coupling is independently controlled by an external coupling magnetic field. Through controlling the parameter of system, the cluster states are generated by this scheme. Also, our approach is convenient for implementing one way quantum computing.
[Show abstract][Hide abstract] ABSTRACT: We show that the rough surface of a microtoroidal cavity (scattering strength) can play a constructive role by studying the entanglement of two atoms surrounding the cavity. Analytical results show that appropriate surface roughness can enhance the atomic entanglement. In particular, the rough surface can also compensate for the loss of maximal entanglement during the evolution caused by cavity leakage and atomic spontaneous emission.
Physical Review A 04/2010; 81(4). DOI:10.1103/PHYSREVA.81.042309 · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, the geometric and dynamic phase components of overall phase induced by 2{\pi} hyperbolic secant pulses in a quantum dot is analyzed. The dependence of two phase components on the ratio of the Rabi frequency to the detuning is investigated. Numerical results indicate that only for one resonant pulse the induced overall phase is purely the geometric phase. With other values of the ratio the overall phase consists of a nonzero dynamic part. The effect of spin precession to decrease the dynamic phase is characterized and discussed by analytical and numerical techniques. Utilizing the symmetry relations of the phases, a scheme to eliminate the dynamic phase by multipulse control is proposed. By choosing the proper parameter for each pulse, the dynamic phases induced by different pulses cancel out. The total pure geometric phase varies from -{\pi} to {\pi}, which realizes the arbitrary geometric rotation of spin. Average fidelity is calculated and the effects of magnetic field and decay of the trion state are compared and discussed. The results show the crucial role of weak magnetic field for high fidelity (above 99.3%). Comment: 7 pages, 8 figures, 1 table
Journal of Physics B Atomic Molecular and Optical Physics 04/2010; 43(12). DOI:10.1088/0953-4075/43/12/125504 · 1.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose a deterministic teleportation protocol of electrons in an array of three quantum-dot molecules. The qubit operations are implemented by sequences of stimulated Raman adiabatic passage (STIRAP) pulses. We show the significant efficiency of the protocol: only one c-NOT gate plus one Hadamard gate is required for the basis transformation, and one single-spin rotation for the reconstruction procedure. Picosecond-scale pulses allow for ultra-short total duration of the protocol, which is far less than the lifetime of electron spin. After only ~5% of the spin-decoherence time the teleportation process can be completed, which implies a high teleportation fidelity.
Journal of Physics B Atomic Molecular and Optical Physics 09/2009; 42(19):195508. DOI:10.1088/0953-4075/42/19/195508 · 1.98 Impact Factor