共查询到20条相似文献,搜索用时 15 毫秒
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We propose an alternative method for the quantum non-demolition measurement of photon numbers wherein weak cross-Kerr nonlinearities are to be used. The usual approach to quantum non-demolition measurements of quantum number involves encoding the photon number, through a cross-Kerr interaction, into a phase shift of a probe coherent state which is then detected through balanced homodyning. Weak nonlinearities produce small phase shifts which are difficult to detect and distinguish. In the method we propose, unbalanced homodyning acts as a displacement operator on the probe beam coherent state such that the cross-Kerr interaction encodes the photon number into the amplitude of a new coherent state. The value of the photon number can be determined by inefficient photon counting on the new coherent state. Our proposed method requires fewer resources than does the usual approach. 相似文献
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《Physics letters. A》2006,359(6):592-596
Aiming the construction of quantum computers and quantum communication systems based on optical devices, in this work we present possible implementations of quantum and classical CNOTs gates, as well an optical setup for generation and distribution of bipartite entangled states, using linear optical devices and photon number quantum non-demolition measurement. 相似文献
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《Physics letters. A》1999,254(6):301-306
A simple scheme for quantum non-demolition (QND) measurement of a Fock state stored in a high-Q cavity is proposed. esscheme utilizes well-defined atomic center-of-mass momentum states in wave propagation direction, interacting with an offresonant cavity field in the Bragg regime. The same scheme can be applied for the formation of quantum Controlled-NOT logic gate. 相似文献
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Scheme for direct measurement of Wigner function in two-mode cavity QED driven by classical fields 下载免费PDF全文
We propose a scheme for the direct measurement of Wigner function in two-mode cavity QED.The atoms are sent to resonantly interact with two orthogonally polarized cavity modes in the presence of strong classical field.The probability of measuring the atom in the ground state directly gives the useful information of the cavity field.This method can be used for quantum non-demolition measurement of the photon number. 相似文献
6.
Jin Shi 《International Journal of Theoretical Physics》2018,57(8):2241-2248
The scheme for joint remote state preparation of two different one-qubit states according to requirement is proposed by using one four-dimensional spatial-mode-entangled KLM state as quantum channel. The scheme for joint remote state preparation of two different two-qubit states according to requirement is also proposed by using one four-dimensional spatial-mode-entangled KLM state and one three-dimensional spatial-mode-entangled GHZ state as quantum channels. Quantum non-demolition measurement, Hadamard gate operation, projective measurement and unitary transformation are included in the schemes. 相似文献
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The reversible transfer of unknown quantum states between light and matter is essential for constructing large-scale quantum networks. Over the last decade, various physical systems have been proposed to realize such quantum memory for light. The solid-state quantum memory based on rare-earth-ion-doped solids has the advantages of a reduced setup complexity and high robustness for scalable application. We describe the methods used to spectrally prepare the quantum memory and release the photonic excitation on-demand. We will review the state of the art experiments and discuss the perspective applications of this particular system in both quantum information science and fundamental tests of quantum physics. 相似文献
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We propose a scheme for generating a genuine four-particle polarisation entangled state ︱χ00 that has many interesting entanglement properties and potential applications in quantum information processing. In our scheme, we use the weak cross-Kerr nonlinear interaction between field-modes and the non-demolition measurement method based on highly efficient homodyne detection, which is feasible under the current experiment conditions. 相似文献
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Shi-Lei Su Long Zhu Qi Guo Hong-Fu Wang Ai-Dong Zhu Shou Zhang Kyu-Hwang Yeon 《Optics Communications》2012,285(20):4134-4139
We present a simplified symmetry analyzer (SA) with cross-Kerr nonlinearity, quantum non-demolition photon number measurement and basic optical elements. Based on the present symmetry analyzer (SA), all the Bell states can be discriminated nondestructively with nearly unity probability. In addition, with the help of cross-phase modulation (XPM) induced by giant cross-Kerr nonlinearity, three-photon Greenberger–Horne–Zeilinger (GHZ) state can also be discriminated determinately and nondestructively, which is supposed to be meaningful in quantum information processing. 相似文献
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Present schemes involving the quantum non-demolition interaction between atomic samples and off-resonant light pulses allow us to store quantum information corresponding to a single harmonic oscillator (mode) in one multi-atomic system. We discuss the possibility of involving several coherences of each atom so that the atomic sample can store information contained in several quantum modes. This is achieved by the coupling of different magnetic sublevels of the relevant hyperfine level by additional Raman pulses. This technique allows us to design not only the quantum non-demolition coupling, but also beam splitter-like and two-mode squeezer-like interactions between light and collective atomic spin. 相似文献
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A phonon counting scheme based on the control of polaritons in an optomechanical system is proposed. This approach permits us to measure the number of phonons in a quantum non-demolition (QND) manner for arbitrary modes not limited by the frequency matching condition as in usual photon-phonon scattering detections. The performance on phonon number transfer and quantum state transfer of the counter are analyzed and simulated numerically by taking into account all relevant sources of noise. 相似文献
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Bidirectional transfer of quantum information for unknown photons via cross-Kerr nonlinearity and photon-number-resolving measurement 下载免费PDF全文
We propose an arbitrary controlled-unitary(CU) gate and a bidirectional transfer scheme of quantum information(BTQI) for unknown photons.The proposed CU gate utilizes quantum non-demolition photon-number-resolving measurement based on the weak cross-Kerr nonlinearities(XKNLs) and two quantum bus beams;the proposed CU gate consists of consecutive operations of a controlled-path gate and a gathering-path gate.It is almost deterministic and is feasible with current technology when a strong amplitude of the coherent state and weak XKNLs are employed.Compared with the existing optical multi-qubit or controlled gates,which utilize XKNLs and homodyne detectors,the proposed CU gate can increase experimental realization feasibility and enhance robustness against decoherence.According to the CU gate,we present a BTQI scheme in which the two unknown states of photons between two parties(Alice and Bob) are mutually swapped by transferring only a single photon.Consequently,by using the proposed CU gate,it is possible to experimentally implement the BTQI scheme with a certain probability of success. 相似文献
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S. Spälter P. van Loock A. Sizmann G. Leuchs 《Applied physics. B, Lasers and optics》1997,64(2):213-218
The optical Kerr effect provides an ideal quantum non-demolition interaction. Experiments and proposals using this interaction
are reviewed with special emphasis on optical soliton pulses propagating in fibres. The performance of a quantum non-demolition
experiment using the optical Kerr effect may be reduced by self-phase modulation of the probe pulse. Proposals to overcome
this limitation are discussed.
Received: 15 April 1996 相似文献
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Measurement-based quantum computation in an optical setup shows great promise towards the implementation oflarge-scale quantum computation. The difficulty of measurement-based quantum computation lies in the preparation ofcluster state. In this paper, we propose the method of generating the large-scale cluster state, which is a platform formeasurement-based quantum computation. In order to achieve more complex quantum circuits, the preparation protocolof N-photon cluster state will be proposed as a generalization of the preparation of four- and five-photon cluster states.Furthermore, our proposal is experimentally feasible. 相似文献
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The theory of unsharp quantum measurements is reviewed as a generalization of the von Neumann-Lüders measurement theory and applied to measurements of continuous quantities. A generalized notion of repeatability is proposed which is applicable even to intrinsically unsharp continuous observables. As an illustration a precise formulation of a quantum non-demolition (QND) measurement performed on a harmonic oscillator is given. 相似文献
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C. V. Usenko 《Optics and Spectroscopy》2011,111(5):678-684
Problem on reconstruction of state of finite-dimension quantum information transfer channel, pure or mixed, by results of
measurements of needed number of observables, is considered. It is shown that in general case it is needed to measure incompatible
observables in number exceeding by one dimension of space of vectors of state. Each of incompatible observables is measured
in its statistically valuable series of measurements. In special case, when one of observables is a non-demolition observable,
measurement of the other observables is needed for realization of control of property of non-demolition. In case of paired
channel it is shown that results of measurements of observables that do not demolish states of sub-channels are characterized
by mutual distribution of probabilities while results of measurement of over-classical observables are characterized by mutual
correlation only. This correlation vanishes completely in case of pure unentangled states. 相似文献
18.
We analyze the quantum measurement properties of dual non-degenerate parametric amplifers in the twin-beam configuration,
in the cascaded back-action-evasion configuration, and in Kerr-type photon-number quantum non-demolition measurements. It
is found that Einstein-Podolsky-Rosen correlations can be obtained between the quadrature components of an idler mode and
the sum of the readout of two signal modes. Furthermore, we discuss dual-mode quantum non-demolition measurements on the combination
of two light modes, and the generation of number-state entanglement.
Received: 12 April 1996/Revised version: 2 July 1996 相似文献
19.
Non-Markovian dynamics detection is one of the most popular subjects in quantum information science. In this paper, a linear -entropy-based non-Markovianity witness scheme is constructed. The positive definiteness of the Choi state will be broken in non-Markovian evolution, which can be witnessed by its linear entropy. Thus, the linear entropy of the Choi state can be used to witness non-Markovian dynamics. The effectiveness of the proposed method is verified using the pure dephasing channel as an example. Finally, it is shown that this method can be extended to the one based on Rényi entropy. 相似文献
20.
We study a readout scheme of a superconducting flux qubit state with a Cooper pair box as a transmon. The qubit states consist of the superpositions of two degenerate states where the charge and phase degrees of freedom are entangled. Owing to the robustness of the transmon against external fluctuations, our readout scheme enables the quantum non-demolition and single-shot measurement of flux qubit states. The qubit state readout can be performed by using the nonlinear Josephson amplifiers after a π/2 rotation driven by an ac electric field. 相似文献