PHASE OPERATOR AND PHASE STATE IN THERMO FIELD DYNAMICS

2009 ◽  
Vol 24 (15) ◽  
pp. 1219-1226 ◽  
Author(s):  
HONG-YI FAN ◽  
NIAN-QUAN JIANG
Keyword(s):  
Coherent States ◽  
Phase State ◽  
Entangled State ◽  
Entangled State Representation ◽  
Phase Operator ◽  
State Representation ◽  
Thermo Field Dynamics ◽  
Limiting Case ◽  
Thermo Entangled State Representation ◽  
Thermo Entangled State

We extend the Susskind–Glogower phase operator and phase state in quantum optics to thermo field dynamics (TFD). Based on the thermo entangled state representation, we introduce thermo excitation and de-excitation operators with which the phase operator and phase state in TFD can be constructed. The phase state treated as a limiting case of a new SU(1, 1) coherent states is also exhibited.

SOLVING MASTER EQUATION FOR CALDEIRA–LEGGETT MODEL BY VIRTUE OF THE THERMO ENTANGLED STATE REPRESENTATION AND THE IWOP TECHNIQUE

2012 ◽  
Vol 26 (14) ◽  
pp. 1250085 ◽  
Author(s):  
QIAN-FAN CHEN ◽  
QIAN YE ◽  
ZHI-HUA LI ◽  
HONG-YI FAN
Keyword(s):  
Master Equation ◽  
Formal Solution ◽  
Quantum Master Equation ◽  
Entangled State ◽  
Iwop Technique ◽  
Entangled State Representation ◽  
State Representation ◽  
Initial State ◽  
Thermo Entangled State Representation ◽  
Thermo Entangled State

In the present work, the exact formal solution of the Caldeira–Leggett quantum master equation for the reduced density matrix of an oscillator is obtained by virtue of the thermo entangled state representation and the technique of integration within an ordered product (IWOP) of operators. Also, the solution for high temperature approximation is derived. When the initial state is a coherent state, it will evolve into a displaced-squeezed chaotic state (a mixed state) which shows that decoherence is involved in the Caldeira–Leggett equation due to the interactions between the system and environment.

APPLICATION OF ENTANGLED STATE IN QUANTIZING SUPERCONDUCTING CAPACITOR MODEL IN THE PRESENCE OF A VOLTAGE BIAS AND A CURRENT BIAS

2004 ◽  
Vol 18 (02) ◽  
pp. 233-240 ◽  
Author(s):  
HONG-YI FAN
Keyword(s):  
Operator Theory ◽  
Hamiltonian Operator ◽  
Entangled State ◽  
Entangled State Representation ◽  
Phase Operator ◽  
State Representation ◽  
Voltage Bias ◽  
A Current

Based on the entangled state representation and the appropriate bosonic phase operator we develop the superconducting capacitor model in the presence of a voltage bias and a current bias. In so doing, the full Hamiltonian operator theory for a superconducting barrier is established.

ON THE ENTANGLED STATE REPRESENTATION, EXCITATION REPRESENTATION AND EFFECTIVE NUMBER-PHASE STATE REPRESENTATIONS IN RINDLER SPACE

2004 ◽  
Vol 19 (34) ◽  
pp. 2587-2594 ◽  
Author(s):  
HONG-YI FAN ◽  
HAI-YAN HE
Keyword(s):  
Phase State ◽  
Vacuum State ◽  
Point Of View ◽  
Entangled State ◽  
Unruh Effect ◽  
Entangled State Representation ◽  
Effective Number ◽  
State Representation ◽  
Commutative Relation ◽  
Rindler Space

We analyze the Unruh effect from the point of view of quantum entanglement. We introduce the entangled state representation in Rindler space and show that the Minkowski vacuum state is an entangled state in Rindler space. The corresponding squeezing operator, which is related to the acceleration of the detector, is obtained naturally. The excitation representation and number state–phase state representations are also introduced in Rindler space. The number-phase commutative relation is established.

THE MIXED COHERENT STATE REPRESENTATION OF THE DENSITY OPERATOR IN THERMO-FIELD DYNAMICS

2007 ◽  
Vol 21 (04) ◽  
pp. 183-188 ◽  
Author(s):  
H.-Y. FAN ◽  
H.-L. LU
Keyword(s):  
Coherent State ◽  
Density Operator ◽  
Master Equations ◽  
Entangled State ◽  
Entangled State Representation ◽  
State Representation ◽  
Thermo Field Dynamics

In the framework of thermo-field dynamics, invented by Umezawa et al., we construct a mixed coherent state representation of density operator ρ. This new representation is useful because it provides an approach to retrieve ρ from its c-number solution of master equations in the entangled state representation.

OPERATOR JOSEPHSON EQUATION FOR A JOSEPHSON JUNCTION CONNECTED INTO A MESOSCOPIC LC CIRCUIT

2008 ◽  
Vol 22 (32) ◽  
pp. 3171-3177
Author(s):  
JI-SUO WANG ◽  
BAO-LONG LIANG ◽  
HONG-YI FAN
Keyword(s):  
Josephson Junction ◽  
Entangled State ◽  
Entangled State Representation ◽  
Phase Operator ◽  
State Representation ◽  
Modified Equations ◽  
Lc Circuit

We find that when a single Josephson junction is inserted into a mesoscopic LC circuit, the operator Josephson equation is modified accompanying with the modification of Farady equation describing the inductance. By virtue of the entangled state representation and using the appropriate phase operator in bosonic form we derive the modified equations.

ENTANGLED STATE REPRESENTATION FOR A PARTICLE ON A CIRCLE STUDIED IN TERMS OF BOSONIC OPERATOR REALIZATION OF ANGULAR MOMENTUM

2006 ◽  
Vol 21 (27) ◽  
pp. 2079-2085 ◽  
Author(s):  
HONG-YI FAN
Keyword(s):  
Quantum Mechanics ◽  
Angular Momentum ◽  
Entangled States ◽  
Entangled State ◽  
Entangled State Representation ◽  
Phase Operator ◽  
State Representation ◽  
New Formalism ◽  
Bosonic Operator ◽  
Operator Realization

By introducing the bosonic operator realization of angular momentum, we establish the entangled state representation for describing quantum mechanics of a particle on a circle. The phase operator, the angular momentum eigenstates, the lowering and ascending operators for angular momentum are all well expressed in the bosonic realization with the aid of appropriate entangled states, i.e. we establish a new formalism for the quantum mechanics of a particle on a circle.

ATOMIC COHERENT STATES AS THE EIGENSTATES OF A TWO-DIMENSIONAL ANISOTROPIC HARMONIC OSCILLATOR IN A UNIFORM MAGNETIC FIELD

2009 ◽  
Vol 24 (38) ◽  
pp. 3129-3136 ◽  
Author(s):  
XIANG-GUO MENG ◽  
JI-SUO WANG ◽  
HONG-YI FAN
Keyword(s):  
Magnetic Field ◽  
Harmonic Oscillator ◽  
Coherent States ◽  
Uniform Magnetic Field ◽  
Hermite Polynomial ◽  
Entangled State ◽  
Two Dimensional ◽  
Entangled State Representation ◽  
Single Variable ◽  
State Representation

In the newly constructed entangled state representation embodying quantum entanglement of Einstein, Podolsky and Rosen, the usual wave function of atomic coherent state ∣τ〉 = exp (μJ+-μ*J-)∣j, -j〉 turns out to be just proportional to a single-variable ordinary Hermite polynomial of order 2j, where j is the spin value. We then prove that a two-dimensional time-independent anisotropic harmonic oscillator in a uniform magnetic field possesses energy eigenstates which can be classified as the states ∣τ〉 in terms of the spin values j.

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