共查询到20条相似文献,搜索用时 62 毫秒
1.
SONG Ke-Hui ZHOU Zheng-Wei GUO Guang-Can 《理论物理通讯》2006,46(4):631-634
We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device (SQUID) qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed in two lower flux states, and the excited state [2〉 would not participate in the procedure. The SQUIDs undergo no transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum iogic in SQUID-system. 相似文献
2.
We present a potential scheme to implement two-qubit quantum phase gates through an unconventional geometric phase shift with two four-level SQUIDs in a cavity. The SQUID qubits undergo no transitions during the gate operation, while the cavity mode is displaced along a circle in the phase space, acquiring a geometric phase depending conditionally upon the SQUIDs’ states. Under certain conditions, the SQUID qubits are disentangled with the cavity mode and the SQUIDs’ states remain in their ground states during the gate operation, thus the gate is insensitive to both the SQUIDs’ “spontaneous emission” and the cavity decay. 相似文献
3.
SONG Ke-Hui ZHOU Zheng-Wei GUO Guang-Can 《理论物理通讯》2006,46(10)
We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device (SQUID) qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum logic in SQUID-system. 相似文献
4.
Based on superconducting quantum interference devices (SQUIDs) coupled to a cavity, we propose a scheme for implementing n SWAP gates simultaneously. In our scheme, the SQUID works in the charge regime, the quantum logic gate operations are performed in the subspace spanned by two charge states |0〉 and |1〉. The interaction between the qubits and the cavity field can be achieved by turning the gate voltage and the external flux. Especially, the gate operation time is independent of the number of the qubits, and the gate operation is insensitive to the initial state of the cavity mode. We also analyze the experimental feasibility that the conditions of the large detuning can be achieved by adjusting the frequency of the cavity mode, and the operation time satisfies the requirement for the designed experiment by choosing suitable detuning and the quality factor of the cavity. Based on the simple operation, our scheme may be realized in this solid-state system, and our idea may be realized in other systems. 相似文献
5.
Quantum controlled phase gate and cluster states
generation via two superconducting quantum interference devices in a
cavity 总被引:3,自引:0,他引:3
Z.-Y. Xue G. Zhang P. Dong Y.-M. Yi Z.-L. Cao 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(3):333-336
A scheme for implementing 2-qubit quantum controlled phase gate (QCPG) is proposed with two superconducting quantum interference
devices (SQUIDs) in a cavity. The gate operations are
realized within the two lower flux states of the SQUIDs by using a quantized cavity field and classical microwave pulses.
Our scheme is achieved without any type of measurement, does not use the cavity mode as the data bus and only requires a very
short resonant interaction of the SQUID-cavity system. As an application of the QCPG operation, we also propose a scheme for
generating the cluster
states of many SQUIDs. 相似文献
6.
One-step implementing three-qubit phase gate via manipulating rf SQUID qubits in the decoherence-free subspace with respect to cavity decay 下载免费PDF全文
We present a scheme for implementing a three-qubit phase
gate via manipulating rf superconducting quantum interference device
(SQUID) qubits in the decoherence-free subspace with respect to
cavity decay. Through appropriate changes of the coupling constants
between rf SQUIDs and cavity, the scheme can be realized only in one
step. A high fidelity is obtained even in the presence of
decoherence. 相似文献
7.
ZHAN Zhi-Ming 《理论物理通讯》2008,49(6):1603-1606
We put forward a simple scheme for one-step realization of
a two-qubit SWAP gate with SQUIDs (superconducting quantum-interference
devices) in cavity QED via Raman transition. In this scheme, the cavity
field is only virtually excited and thus the cavity decay is suppressed. The
SWAP gate is realized by using only two lower flux states of the SQUID system
and the excited state would not be excited. Therefore, the effect of
decoherence caused from the levels of the SQUID system is possibly
minimized. The scheme can also be used to implement the SWAP gate with
atoms. 相似文献
8.
SONG Ke-Hui ZHOU Zheng-Wei GUO Guang-Can 《理论物理通讯》2007,47(5):821-825
Based on superconducting quantum interference devices (SQUIDs) coupled to a cavity, we propose a scheme for implementing a quantum controlled-phase gate (QPG) and Deutsch-Jozsa (D J) algorithm by a controllable interaction. In the present scheme, the SQUID works in the charge regime, and the cavity field is ultilized as quantum data-bus, which is sequentially coupled to only one qubit at a time. The interaction between the selected qubit and the data bus, such as resonant and dispersive interaction, can be realized by turning the gate capacitance of each SQUID. Especially, the bus is not excited and thus the cavity decay is suppressed during the implementation of DJ algorithm. For the QPG operation, the mode of the bus is unchanged in the end of the operation, although its mode is really excited during the operations. Finally, for typical experiment data, we analyze simply the experimental feasibility of the proposed scheme. Based on the simple operation, our scheme may be realized in this solid-state system, and our idea may be realized in other systems. 相似文献
9.
ZHAN Zhi-Ming 《理论物理通讯》2010,54(2):355-358
We propose a scheme to generate the W states with manySQUIDs (superconducting-quantum-interference-devices) in cavity QED viaRaman transition. In this scheme, the transfer of quantum informationbetween the SQUIDs and cavity is not required. And the cavity field is onlyvirtually excited, thus the cavity decay is suppressed during the W statesgeneration. The SQUIDs are always populated in the two ground states.Therefore, the scheme is insensitive to the spontaneous emission of theexcited level of the SQUID and cavity decay. 相似文献
10.
We propose a method of realizing a three-qubit quantum gate with a superconducting quantum interference device(SQUID) in a cavity.In this proposal,the gate operation involves the SQUID ground-states and the Fock states of cavity modes b and c.The two field-modes act as the controlling qubits,and the two SQUID states form the target qubit.Since only the metastable lower levels are involved in the gate operation,the gate is not affected by the SQUID decay rates. 相似文献
11.
We presented a scheme to implement SWAP gate in a microwave cavity. In our scheme, two superconducting quantum interference
device (SQUID) qubits are coupled to a single-mode microwave cavity field by adiabatic passage method for their manipulation.
This process of implementing SWAP gate is in the range of present experiments. The scheme can be easily obtained only by three
steps, which does not require perform any operation. In the scheme, the operations only involve three lowest flux states of
the SQUIDs, and the excited states would not be excited; therefore, the decoherence due to spontaneous emission of the SQUIDs’
levels would not affect the operations. In addition, during the whole procedure the cavity field is not necessary to be excited
because it does not require transfer quantum information between the SQUID’s and the cavity field. Thus, the cavity decay
is suppressed. Therefore our scheme may be realized in superconducting systems. 相似文献
12.
We revisit a theoretical scheme to create quantum entanglement of two
three-level superconducting quantum interference devices (SQUIDs) with the
help of an auxiliary SQUID. In this scenario, two three-level systems are
coupled to a quantized cavity field and a classical external field and thus
form dark states. The quantum entanglement can be produced by a quantum measurement on the auxiliary SQUID. Our investigation emphasizes the quantum effect of the auxiliary SQUID. For the experimental feasibility and
accessibility of the scheme, we calculate the time evolution of the whole system including the auxiliary SQUID. To ensure the efficiency of generating quantum entanglement, relations between the measurement time and dominate parameters of the system are analyzed according to detailed calculations. 相似文献
13.
We propose a transistorlike circuit including two serially connected segments of a narrow superconducting nanowire joint by a wider segment with a capacitively coupled gate in between. This circuit is made of amorphous NbSi film and embedded in a network of on-chip Cr microresistors ensuring a sufficiently high external electromagnetic impedance. Assuming a virtual regime of quantum phase slips (QPS) in two narrow segments of the wire, leading to quantum interference of voltages on these segments, this circuit is dual to the dc SQUID. Our samples demonstrated appreciable Coulomb blockade voltage (analog of critical current of the SQUIDs) and periodic modulation of this blockade by an electrostatic gate (analog of flux modulation in the SQUIDs). The model of this QPS transistor is discussed. 相似文献
14.
15.
Implementation of a Controlled-NOT Gate Using Superconducting Quantum Interference Devices 下载免费PDF全文
A scheme is proposed for implementing a controlled-NOT gate via superconducting quantum interference device (SQUID) in cavity-QED. The controlled-NOT gate can be achieved by coupling the SQUID to a single-mode microwave cavity field or classical microwave pluses. The scheme may be experimentally realizable. 相似文献
16.
ZHAN Zhi-Ming 《理论物理通讯》2007,47(4):722-724
In this paper, a scheme is proposed to create the entanglement of two superconducting quantum-interference devices (SQUIDs) and implement a two-quhit quantum phase gate between two SQUIDs in cavity. The scheme only requires resonant interactions. Thus the scheme is very simple and the quantum dynamics operation can he realized at a high speed, which is important in view of decoherence. 相似文献
17.
Realization of Greenberg-Horne-Zeilinger (GHZ) and W Entangled States with Multiple Superconducting Quantum-Interference Device Qubits in Cavity QED 下载免费PDF全文
An alternative scheme is proposed for generating the Greenberg-Horne-Zeilinger (GHZ) and W types of the entangled states with multiple superconducting quantum-interference device (SQUID) qubits in a single-mode microwave cavity field. In this scheme, there is no transfer of quantum information between the SQUIDs and the cavity, the cavity is always in the vacuum and thus the requirement on the quality of cavity is greatly loosened. In addition, during the process of the generation of the W entangled state, the present method does not involve a real excitation of intermediate levels. Thus, decoherence due to energy relaxation of intermediate levels is minimized. 相似文献
18.
YANG Wen-Xing CHEN Ai-Xi 《理论物理通讯》2008,49(4):913-918
In the system with superconducting quantum interference devices (SQUID) in cavity, a scheme for constructing two-qubit quantum phase gate via a conventional geometric phase-shift is proposed by using a quantized cavity field and classical microwave pulses. In this scheme, the gate operation is realized in the subspace spanned by the two lower flux states of the SQUID system mud the population operator of the excited state has no effect on it. Thus the effect of decoherence caused from the levels of the SQUID system is possible to minimize. Under cavity decay, our strictly numerical simulation shows that it is also possible to realize the unconventional geometric phase gate. The experimental feasibility is discussed in detail. 相似文献
19.
20.
SONG Ming-Yu 《理论物理通讯》2011,56(5):837-844
We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating the cluster states with rf superconducting quantum interference devices (SQUIDs) coupled to a microwave cavity through adiabatic evolution of dark eigenstates. During the operation, the spontaneous emission is suppressed since the rf SQUIDs are always in the three lowest flux states. Considering the influence from the cavity decay with achievable
experimental parameters, we numerically analyze the success probability and the fidelity for generating the two-SQUID maximally entangled state and the controlled phase-shift gate by adiabatic passage. 相似文献