QUANTUM FLUCTUATION IN THERMAL VACUUM STATE FOR MESOSCOPIC DISTRIBUTED PARAMETER CIRCUITS

2005 ◽  
Vol 19 (10) ◽  
pp. 1731-1740 ◽  
Author(s):  
YING-HUA JI ◽  
HAI-MEI LUO ◽  
YI-FAN WANG ◽  
JIAN-MO WANG
Keyword(s):  
Thermal Field ◽  
Unitary Operator ◽  
Quantum Noise ◽  
Quantum Fluctuation ◽  
Vacuum State ◽  
Distributed Parameter ◽  
Thermal Vacuum ◽  
Distributed Parameter Circuit ◽  
Field Dynamic ◽  
Periodic Transmission

In this paper we consider a non-dissipative distributed parameter circuit at a finite temperature T. We find the unitary operator for diagonalizing the Hamiltonian of the uniform periodic transmission line. The unitary operator is expressed in a coordinate representation. Thermal field dynamic is used in our discussion. It is shown that distributing parameter circuits and quantum fluctuations, which also have distributing properties, are related to both the circuit parameters and the positions and the model of signals and temperature T. The higher the temperature, the more quantum noise the circuit exhibits. The research will be helpful to miniaturize intergreate circuits and electric components. It will be also significant for the futher study of the qualitities of mesoscopic system.

FLUCTUATIONS AT FINITE TEMPERATURE AND THERMODYNAMICS OF MESOSCOPIC RLC CIRCUIT CALCULATED BY USING GENERALIZED THERMAL VACUUM STATE

2011 ◽  
Vol 25 (31) ◽  
pp. 2353-2361 ◽  
Author(s):  
HONG-CHUN YUAN ◽  
XUE-XIANG XU ◽  
XUE-FEN XU ◽  
HONG-YI FAN
Keyword(s):  
Thermal Field ◽  
Quantum Noise ◽  
Vacuum State ◽  
Nonzero Temperature ◽  
Thermal Vacuum ◽  
Partial Trace ◽  
Expectation Value ◽  
Rlc Circuit ◽  
Thermal Vacuum State ◽  
Mesoscopic Rlc Circuit

By using the partial trace method and the technique of integration within an ordered product of operators we obtain the explicit expression of the generalized thermal vacuum state (GTVS) for an RLC circuit instead of using the Takahashi–Umezawa approach. According to thermal field dynamics (TFD), namely, the expectation value of physical observables in this GTVS is equivalent to their ensemble average, based on GTVS we successfully derive the quantum fluctuations at nonzero temperature and the thermodynamical relations for the mesoscopic RLC circuit. Our results show that the higher the temperature is, the more quantum noise the RLC circuit exhibits.

Quantum Fluctuation in Thermal Vacuum State for Nondissipative Mesoscopic Capacitance Coupling Circuit

2003 ◽  
Vol 17 (15) ◽  
pp. 821-828
Author(s):  
Tong-Qiang Song
Keyword(s):  
Finite Temperature ◽  
Thermal Field ◽  
Quantum Fluctuation ◽  
Vacuum State ◽  
Thermal Vacuum ◽  
Coupling Circuit ◽  
Thermal Vacuum State ◽  
Capacitance Coupling

By means of the thermal field dynamics (TDF) theory we study the quantum fluctuation of a nondissipative mesoscopic capacitance coupling circuit at a finite temperature.

Quantum Fluctuation of Mesoscopic Capacitance Coupled Circuit in a Thermal Vacuum State

2003 ◽  
Vol 20 (12) ◽  
pp. 2231-2234
Author(s):  
Zhu Ai-Dong ◽  
Zhang Shou ◽  
Jin Zhe ◽  
Zhao Yong-Fang ◽  
Jing Xiao-Gong ◽  
...  
Keyword(s):  
Quantum Fluctuation ◽  
Vacuum State ◽  
Thermal Vacuum ◽  
Thermal Vacuum State

QUANTUM FLUCTUATION OF TWO-MODE SQUEEZED THERMAL VACUUM STATES AND THE THERMAL WIGNER OPERATOR STUDIED BY VIRTUE OF <η| REPRESENTATION

2001 ◽  
Vol 15 (12n13) ◽  
pp. 397-406 ◽  
Author(s):  
HONGYI FAN ◽  
HUI WANG
Keyword(s):  
Thermal Effect ◽  
Quantum Fluctuation ◽  
Vacuum State ◽  
Thermal Vacuum ◽  
Wigner Operator ◽  
Squeezed Vacuum State ◽  
Squeezed Vacuum ◽  
Thermo Field Dynamics ◽  
Vacuum States

Based on the <η| representation in Thermo Field Dynamics3 we introduce the thermal Wigner operator, with which we reach the conclusion that due to the thermal effect the quantum fluctuation of two-mode squeezed vacuum state increases by a factor cosh 2θ, where tanh θ = exp (-ℏω/2kT). We also mathematically analyse the formalism of Thermo Field Dynamics in the context of entanglement theory.

Transmission Line Theories for the Analysis of Electromagnetic Transients in Coil Windings

2013 ◽  
pp. 1-44
Author(s):  
Akihiro Ametani ◽  
Teruo Ohno
Keyword(s):  
Transmission Line ◽  
Propagation Constant ◽  
Characteristic Impedance ◽  
Electromagnetic Transients ◽  
Distributed Parameter ◽  
System A ◽  
Three Phase ◽  
Distributed Parameter Circuit ◽  
Transformer Winding ◽  
Phase Transmission

The chapter contains the basic theory of a distributed-parameter circuit for a single overhead conductor and for a multi-conductor system, which corresponds to a three-phase transmission line and a transformer winding. Starting from a partial differential equation of a single conductor, solutions of a voltage and a current on the conductor are derived as a function of the distance from the sending end. The characteristics of the voltage and the current are explained, and the propagation constant (attenuation and propagation velocity) and the characteristic impedance are described. For a multi-conductor system, a modal theory is introduced, and it is shown that the multi-conductor system is handled as a combination of independent single conductors. Finally, a modeling method of a coil is explained by applying the theories described in the chapter.

scholarly journals Proposal of a Computational Approach for Simulating Thermal Bosonic Fields in Phase Space

Physics ◽  
2019 ◽  
Vol 1 (3) ◽  
pp. 402-411 ◽  
Author(s):  
Alessandro Sergi ◽  
Roberto Grimaudo ◽  
Gabriel Hanna ◽  
Antonino Messina
Keyword(s):  
Phase Space ◽  
Thermal Noise ◽  
Fock Space ◽  
Vacuum State ◽  
Thermal Bath ◽  
Wigner Transform ◽  
Thermal Vacuum ◽  
Thermo Field Dynamics ◽  
Augmented Space ◽  
Thermal Vacuum State

When a quantum field is in contact with a thermal bath, the vacuum state of the field may be generalized to a thermal vacuum state, which takes into account the thermal noise. In thermo field dynamics, this is realized by doubling the dimensionality of the Fock space of the system. Interestingly, the representation of thermal noise by means of an augmented space is also found in a distinctly different approach based on the Wigner transform of both the field operators and density matrix, which we pursue here. Specifically, the thermal noise is introduced by augmenting the classical-like Wigner phase space by means of Nosé–Hoover chain thermostats, which can be readily simulated on a computer. In this paper, we illustrate how this may be achieved and discuss how non-equilibrium quantum thermal distributions of the field modes can be numerically simulated.

THERMOFIELD ANALYSIS OF MAGNON SQUEEZING STATE IN THE FERROMAGNET

2008 ◽  
Vol 22 (20) ◽  
pp. 1931-1939
Author(s):  
QINFENG XU ◽  
ZE CHENG ◽  
YUNXIA PING
Keyword(s):  
Thermal Field ◽  
Zero Point ◽  
Vacuum State ◽  
Field Approximation ◽  
Spin Component ◽  
Zero Temperature ◽  
Temperature Dependent ◽  
Consistent Field ◽  
Self Consistent Field ◽  
Lower Temperature

In this paper, we introduce the self-consistent field approximation to treat with the nonlinear interaction among spin waves. Then temperature-dependent Bogoliubov transformation is introduced to generate a new representation which engenders the transition from the zero temperature to the finite temperature. At last, temperature-dependent quantum fluctuation properties of magnons are discussed in the thermal field. At lower temperature, we find that the fluctuation of spin-component at some given time regions can be below the zero-point fluctuation level of the vacuum state and exhibit a periodical squeezing behavior. In particular, these squeezed effects vanish with the increasing of temperature. These squeezing effects differ from the previous studies.

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