共查询到20条相似文献,搜索用时 225 毫秒
1.
YANG Zhen-Biao 《理论物理通讯》2005,44(6):1073-1075
We present an alternative scheme for preparing the superpositions of coherent states along a straight line of a cavity field using degenerate atom-cavity field Raman interaction. In the scheme, a collection of A-type three-level atoms is orderly sent through the cavity to interact with the cavity field adjusted by a microwave source connected to it, followed by state-selective measurements. In this way, we can prepare the superpositions of several coherent states along a straight line with arbitrary weighting factors for the cavity field. In the scheme, the coherence of the atom-cavity system may be maintained and the second microwave field is unnecessary, which is prior to the previous scheme. 相似文献
2.
YANG Zhen-Biao 《理论物理通讯》2005,44(12)
We present an alternative scheme for preparing the superpositions of coherent states along a straight line of a cavity field using degenerate atom-cavity field Raman interaction. In the scheme, a collection of A-type three-level atoms is orderly sent through the cavity to interact with the cavity field adjusted by a microwave source connected to it, followed by state-selective measurements. In this way, we can prepare the superpositions of several coherent states along a straight line with arbitrary weighting factors for the cavity field. In the scheme, the coherence of the atom-cavity system may be maintained and the second microwave field is unnecessary, which is prior to the previous scheme. 相似文献
3.
Andersen MF Ryu C Cladé P Natarajan V Vaziri A Helmerson K Phillips WD 《Physical review letters》2006,97(17):170406
We demonstrate the coherent transfer of the orbital angular momentum of a photon to an atom in quantized units of variant Planck's over 2pi, using a 2-photon stimulated Raman process with Laguerre-Gaussian beams to generate an atomic vortex state in a Bose-Einstein condensate of sodium atoms. We show that the process is coherent by creating superpositions of different vortex states, where the relative phase between the states is determined by the relative phases of the optical fields. Furthermore, we create vortices of charge 2 by transferring to each atom the orbital angular momentum of two photons. 相似文献
4.
S. A. Podoshvedov 《Journal of Experimental and Theoretical Physics》2012,114(3):451-464
We study the method of generation of states that approximate superpositions of large-amplitude coherent states (SCSs) with
high fidelity in free-traveling fields. Our approach is based on the representation of an arbitrary single-mode pure state,
and SCSs in particular, in terms of displaced number states with an arbitrary displacement amplitude. The proposed optical
scheme is based on alternation of photon additions and displacement operators (in the general case, N photon additions and N − 1 displacements are required) with a seed coherent state to generate both even and odd displaced squeezed SCSs regardless
of the parity of the used photon additions. It is shown that the optical scheme studied is sensitive to the seed coherent
state if the other parameters are unchanged. Output states can approximate either even squeezed SCS or odd SCS shifted relative
to each other by some value. This allows constructing a local rotation operator, in particular, the Hadamard gate, which is
a mainframe element for quantum computation with coherent states. We also show that three-photon additions with two intermediate
displacement operators are sufficient to generate even displaced squeezed SCS with the amplitude 1.7 and fidelity more than
0.99. The effects deteriorating the quality of output states are considered. 相似文献
5.
Quantum state engineering by superpositions of coherent states along a straight line with a single atomic state measurement 总被引:1,自引:0,他引:1
A new scheme is proposed for preparation of a type of nonclassical state in cavity QED. In the scheme, an atom either flying through or trapped within a cavity, is controlled by the classical Stark effect; this makes it interact alternately with a (resonant) classical field and with the (dispersive) cavity field. The cavity field, which allows an arbitrary displacement operation during the process, after the detection on the atom, finally collapses to the specific superpositions of coherent states, with their weighting factors controllable. The scheme is also applied for preparation of superpositions of motional coherent states for a trapped ion. The scheme is in contrast to all the previous ones, and thus provides a new perspective for quantum state engineering. 相似文献
6.
Generation of any superposition of coherent states along a straight line via resonant atom-cavity interaction 下载免费PDF全文
This paper proposes a scheme for generating arbitrary
superpositions of several coherent states along a straight line for
a cavity mode. In the scheme, several atoms are sent through a
cavity initially in a strong coherent state. The superposition of
several coherent states with desired coefficients may be generated
if each atom is detected in the excited state after it exits the
cavity. The scheme is based on resonant atom--cavity interaction and
no classical field is required during and after the atom--cavity
interaction. Thus, the scheme is very simple and the interaction
time is very short, which is important in view of decoherence. 相似文献
7.
P. Horak H. Ritsch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):279-287
We propose a method to create macroscopic superpositions, so-called Schr?dinger cat states, of different motional states of
an ideal Bose-Einstein condensate. The scheme is based on the scattering of a freely expanding condensate by the light field
of a high-finesse optical cavity in a quantum superposition state of different photon numbers. The atom-photon interaction
creates an entangled state of the motional state of the condensate and the photon number, which can be converted into a pure
atomic Schr?dinger cat state by operations only acting on the cavity field. We discuss in detail the fully quantised theory
and propose an experimental procedure to implement the scheme using short coherent light pulses.
Received 26 June 2000 and Received in final form 2nd October 2000 相似文献
8.
We study analytically the generation of maximally entangled states (MESs) formed by a two-component Bose-Einstein condensate (BEC) trapped in an adiabatically driven single potential well. Under the condition of the linear interaction controlled by a driven field being much stronger than the effective nonlinear interaction between the components, MESs, as some particular cases of superpositions of spin coherent states (SSCS), may emerge periodically along with not only time evolution but also the equidifferent change of the linear coupling strength at a particular time. 相似文献
9.
Shi-Biao Zheng 《Physica A》1998,260(3-4)
We propose a scheme for generating superpositions of two pair coherent states of a two-mode field. In the scheme an atom is sent through a cavity initially in a pair coherent state. The state-selective measurement following the two-mode Raman process projects the two-mode field to a pair cat state. 相似文献
10.
We present a scheme to generate a squeezed atom laser via stimulated Raman transition of the atoms in Bose-Einstein condensate (BEC) interacting with two light beams, including a weaker squeezed coherent probe light and a stronger classical pump light. The results show that the quantum fluctuation of this atom laser can be periodically squeezed. The squeezing depth of such atom laser is determined by the initial squeezing factor of the probe light, and the squeezing period of that is related to the mean number of atoms in the trap, the strength of interaction between squeezing light and BEC atoms, and the detuning of the light. 相似文献
11.
We propose a scalable procedure to generate superpositions of motional coherent states and also entangled vibronic states in N trapped ions. Beyond their fundamental importance, these states may be of interest for quantum information processing and may be used in experimental studies on decoherence. 相似文献
12.
This paper proposes a scheme for generation of superpositions of
coherent states of the effective bosonic mode in a collection of
atoms. In the scheme an atomic sample interacts with a slightly
detuned cavity mode and a resonant strong classical field. Under
certain conditions the atomic system evolves from a coherent state
to a superposition of coherent states. 相似文献
13.
YANG Wen-Xing 《理论物理通讯》2006,46(8)
We propose a scheme to generate a superposition of motional coherent states with arbitrary coefficients on a line in phase space and implement a quantum controlled phase-gate for multiple trapped ions with a single standing-wave laser pulse whose carrier frequency is tuned to the ions transition. In the scheme each ion does not need to be exactly positioned at the node of the standing wave, which is very important from viewpoint of experiment. Furthermore, our scheme may allow the generation of a superposition of coherent states with large mean phonon number for a large number of trapped ions in a fast way by choosing suitable laser intensity. We show that it can also be used to generate maximally entangled states of multiple trapped ions. 相似文献
14.
YANG Wen-Xing 《理论物理通讯》2006,46(2):297-302
We propose a scheme to generate a superposition of motional coherent states with arbitrary coefficients on a line in phase space and implement a quantum controlled phase-gate for multiple trapped ions with a single standing-wave laser pulse whose carrier frequency is tuned to the ions transition. In the scheme each ion does not need to be exactly positioned at the node of the standing wave, which is very important from viewpoint of experiment, Furthermore, our scheme may allow the generation of a superposition of coherent states with large mean phonon number for a large number of trapped ions in a fast way by choosing suitable laser intensity. We show that it can also be used to generate maximally entangled states of multiple trapped ions. 相似文献
15.
ZHENG Shi-Biao 《理论物理通讯》2005,44(12)
We propose a method for the generation of superpositions of two-mode coherent states for the center-of-mass and relative vibrational modes of two trapped ions. In the scheme the ions are driven by a single travelling-wave laser field tuned to the carrier. Then a measurement of the internal states collapses the vibrational modes to the entangled coherent state. 相似文献
16.
ZHENG Shi-Biao 《理论物理通讯》2005,44(6):1071-1072
We propose a method for the generation of superpositions of two-mode coherent states for the center-of-mass and relative vibrational modes of two trapped ions. In the scheme the ions are driven by a single travelling-wave laser field tuned to the carrier. Then a measurement of the internal states collapses the vibrational modes to the entangled coherent state. 相似文献
17.
Preparation of nonclassical states and measurement of the Wigner function for the collective motion of N trapped ions 下载免费PDF全文
We propose a scheme for generating nonclassical states for the centre-of-mass vibrational mode of N trapped ions,including superpositions of several coherent states on a circle and Fock states. In the scheme N trapped ions are driven by a laser beam tuned to the carrier. The scheme also provides a new prospect for laser cooling. The scheme can be used to measure the Wigner function of the collective vibrational mode. 相似文献
18.
《Physics letters. A》1998,244(6):512-516
We propose a cavity QED technique to generate superpositions of a series of coherent states on a circle through the interaction of the cavity field with only one atom driven by a classical field. 相似文献
19.
We show how to convert between partially coherent superpositions of a single photon with the vacuum by using linear optics and postselection based on homodyne measurements. We introduce a generalized quantum efficiency for such states and show that any conversion that decreases this quantity is possible. We also prove that our scheme is optimal by showing that no linear optical scheme with generalized conditional measurements, and with one single-rail qubit input, can improve the generalized efficiency. 相似文献
20.
It is well known that spontaneous parametric down-conversion can be used to probabilistically prepare single-photon states. We have performed an experiment in which arbitrary superpositions of zero- and one-photon states can be prepared by appropriate postselection. The optical phase, which is meaningful only for superpositions of photon number, is related to the relative phase between the zero- and one-photon states. Whereas the light from spontaneous parametric down-conversion has an undefined phase, we show that this technique collapses one beam to a state of well-defined optical phase when a measurement succeeds on the other beam. 相似文献