共查询到20条相似文献,搜索用时 0 毫秒
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Mukamel S 《Physical review letters》2003,90(17):170604
The relation between the distribution of work performed on a classical system by an external force switched on an arbitrary time scale and the corresponding equilibrium free energy difference is generalized to quantum systems. Using the adiabatic representation, we show that this relation holds for isolated systems as well as for systems coupled to a bath described by a master equation. A close formal analogy is established between the present "classical trajectory" picture over populations of adiabatic states and phase fluctuations (dephasing) of a quantum coherence in spectral line shapes, described by the stochastic Liouville equation. 相似文献
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A spatially multimode scheme of the quantum memory for light is presented that can be considered to be a thin hologram, whose long-lived spin subsystem of a multiatomic ensemble stores image peculiarities, such as the multimode superposition and entangled quantum states, which is unattainable for ordinary holography. In the recording process, the measurement of polarization parameters of the transmitted light wave and the feedback are used for the action on an ensemble of fixed atoms (obtained, for example, by means of the laser cooling). The information capacity of a quantum hologram with a feedback will considerably exceed that of a spatially singlemode quantum memory. 相似文献
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提出一种基于半导体激光器泵浦Nd∶YAG微片激光器的回馈干涉系统,适合于非配合目标的位移和绝对距离测量。该测量系统包括移频回馈干涉光学系统,基于泵浦调制的微片激光器调频系统和相敏检波信号处理系统3部分。介绍了移频回馈干涉的原理,给出了位移测量和绝对距离测量应用的原理和测量方法,分析了测量的分辨率。实际测量了发黑工件表面的位移和绝对距离。实验结果表明,该回馈干涉系统灵敏度高,对被测表面反射率的要求很低,兼有对非配合目标的高分辨率位移测量和绝对距离测量的能力。 相似文献
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Basim Abdullattif Ghalib Sabri J. Al-Obaidi Amin H. Al-Khursan 《Superlattices and Microstructures》2012
The optoelectronic feedback (OEF) in quantum dot semiconductor lasers (QD SLs) is studied theoretically where a model includes wetting layer ground state and excited state for QDs are included separating electrons and holes in their dynamics. Both positive and negative OEF are studied. The time series of photon density, the phase portraits of carriers in the states are studied. The parameters affecting OEF are examined where an excitability is seen. The QD SL is found to be more sensitive to the changes in time delay compared with other SLs and a complicated routs are seen in the behavior of QD SL. 相似文献
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We study a dissipative quantum mechanical model of the projective measurement of a qubit. We demonstrate how a correspondence limit, damped quantum oscillator can realise chaotic-like or periodic trajectories that emerge in sympathy with the projection of the qubit state, providing a model of the measurement process. 相似文献
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In this paper multiple delay feedback control (MDFC) with different
and independent delay times is shown to be an efficient method for
stabilizing fixed points in finite-dimensional dynamical systems.
Whether MDFC can be applied to infinite-dimensional systems has been
an open question. In this paper we find that for infinite-dimensional
systems modelled by delay differential equations, MDFC works well for
stabilizing (unstable) steady states in long-, moderate- and
short-time delay regions, in particular for the hyperchaotic case. 相似文献
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Yanagisawa M 《Physical review letters》2006,97(19):190201
We present quantum feedback control for deterministic entanglement generation at the single-photon level. The protocol of controlling both total photon number and phase difference is based on the cascade structure of cavities placed in an optical closed loop, quantum nondemolition measurement with cross-Kerr interactions, and Lyapunov stability for feedback design. 相似文献
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Wendy Flores-Fuentes Oleg Sergiyenko Félix F. Gonzalez-Navarro Moisés Rivas-López Daniel Hernandez-Balbuena Julio C. Rodríguez-Quiñonez Vera Tyrsa Lars Lindner 《Optical Review》2016,23(6):891-896
3D measurement by a cyber-physical system based on optoelectronic scanning instrumentation has been enhanced by outliers and regression data mining feedback. The prototype has applications in (1) industrial manufacturing systems that include: robotic machinery, embedded vision, and motion control, (2) health care systems for measurement scanning, and (3) infrastructure by providing structural health monitoring. This paper presents new research performed in data processing of a 3D measurement vision sensing database. Outliers from multivariate data have been detected and removal to improve artificial intelligence regression algorithm results. Physical measurement error regression data has been used for 3D measurements error correction. Concluding, that the joint of physical phenomena, measurement and computation is an effectiveness action for feedback loops in the control of industrial, medical and civil tasks. 相似文献
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We further elaborate on the device proposed by Karimi et al. [15], in which coupled superconducting qubits can play the role of a quantum heat switch. In the present paper we analyze the performances of the switch if the number of qubits increases considering in details the cases of three and four qubits. To this aim we study the effect of the number of qubits on the transmitted power between baths. As the number of qubits increases, the transmitted power between baths increases as well. 相似文献
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In sinusoidal phase modulating laser diode (LD) interferometer, the injection current of the LD is sinusoidally modulated to realize the modulation of the wavelength. However, the light intensity of LD is also modulated, which affects the measurement accuracy. An all-fiber sinusoidal phase modulating LD interferometer for real-time displacement measurement is proposed where the influence of the intensity modulation is eliminated with a new algorithm. It is made clear that an optimal depth of the sinusoidal phase modulation (SPM) exists in the algorithm. Moreover, the SPM depth is locked at the optimal value by controlling the injection current with a feedback control system. The feasibility of the proposed interferometer for displacement measurement is verified by experiments. 相似文献
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We investigate that no-knowledge measurement-based feedback control is utilized to obtain the estimation precision of the detection efficiency. We show that no-knowledge measurement is the optimal way to estimate the detection efficiency.The higher precision can be achieved for the lower or larger detection efficiency. It is found that no-knowledge feedback can be used to cancel decoherence. No-knowledge feedback with a high detection efficiency can perform well in estimating frequency and detection efficiency parameters simultaneously; simultaneous estimation is better than independent estimation given by the same probes. 相似文献
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John F. Cyranski 《Foundations of Physics》1978,8(11-12):805-822
It is assumed that experiments yield results that are not isomorphic with reality, but represent a distorted image of reality. Reality is related to observation via a communication channel of finite capacity. Quantum uncertainties are due to the bound on the amount of information available. Use is made of recent results from information and communication theories. 相似文献
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Benjamin Fain 《Foundations of Physics Letters》1997,10(3):221-233
The prerequisite of quantum measurement is a transformation of an initially off-diagonal density matrix
ρmα;nβ
describing an interacting measured object and measuring device into a diagonal density matrix
ρmα;mαδmnδαβ
. The latter density matrix describes a proper mixture of states having definitem-values. On the other hand, the irreversible relaxation (towards the thermodynamic equilibrium) is also characterized by transformation
of an initially off-diagonal matrix into a diagonal one. It has been shown that the process of irreversible relaxation can
be used to perform quantum measurement, provided the duration Δt of the measurement is much larger thanT
2, the phase relaxation time, and much smaller thanT
1, the population relaxation time:T
2 ≪ Δt ≪T
1. Agedanken experiment describing this kind of measurement is provided. Aπ/2-pulse transforms an initials
z
= −1/2 state into superposition ofs
z
= ±1/2 states. The irreversible relaxation leads to the proper mixture ofs
z
= 1/2 ands
z
= −1/2 state. Results of the measurements are verified by the second electromagnetic pulse. 相似文献
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