scholarly journals A New Mechanism of Open System Evolution and Its Entropy Using Unitary Transformations in Noncomposite Qudit Systems

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 736 ◽  
Author(s):  
Julio A. López-Saldívar ◽  
Octavio Castaños ◽  
Margarita A. Man’ko ◽  
Vladimir I. Man’ko
Keyword(s):  
Open System ◽  
Type System ◽  
Quantum Channels ◽  
Probability Representation ◽  
Experimental Realization ◽  
System Evolution ◽  
Phase Damping ◽  
Level Atom ◽  
Unitary Transformations ◽  
Unitary Transform

The evolution of an open system is usually associated with the interaction of the system with an environment. A new method to study the open-type system evolution of a qubit (two-level atom) state is established. This evolution is determined by a unitary transformation applied to the qutrit (three-level atom) state, which defines the qubit subsystems. This procedure can be used to obtain different qubit quantum channels employing unitary transformations into the qutrit system. In particular, we study the phase damping and spontaneous-emission quantum channels. In addition, we mention a proposal for quasiunitary transforms of qubits, in view of the unitary transform of the total qutrit system. The experimental realization is also addressed. The probability representation of the evolution and its information-entropic characteristics are considered.

Open system evolution and “memory dressing”

2004 ◽  
Vol 69 (1) ◽  
Author(s):  
Irena Knezevic ◽  
David K. Ferry
Keyword(s):  
Open System ◽  
System Evolution

AN ALGEBRAIC APPROACH TO THE INTERACTION OF A THREE-LEVEL ATOM INTERACTING WITH QUANTIZED RADIATION FIELD

2000 ◽  
Vol 14 (14) ◽  
pp. 1459-1471
Author(s):  
XU-BO ZOU ◽  
JING-BO XU ◽  
XIAO-CHUN GAO ◽  
JIAN FU
Keyword(s):  
Algebraic Structure ◽  
Evolution Operator ◽  
Algebraic Approach ◽  
Algebraic Method ◽  
Time Evolution Operator ◽  
Level Atom ◽  
Unitary Transformations ◽  
Quantized Field ◽  
Quantized Radiation Field ◽  
Multiphoton Interaction

The system of a three-level atom in the Ξ configuration coupled to two quantized field modes with arbitrary detuning and density-dependent multiphoton interaction is studied by dynamical algebraic method. With the help of an su(3) algebraic structure, we diagonalize the Hamiltonian by making use of unitary transformations and obtain the eigenvalues, eigenstates and time evolution operator for the system. Based on this su(3) structure, we also show that the system of a three-level atom in the Ξ configuration can be exactly transformed to an effective two-level Hamiltonian by an unitary transformation. Finally, we show that there exist an su (N) algebraic structure in the system of a N-level atom interacting with N-1 field modes.

scholarly journals QUANTUM SECURE CONDITIONAL DIRECT COMMUNICATION VIA EPR PAIRS

2005 ◽  
Vol 16 (08) ◽  
pp. 1293-1301 ◽  
Author(s):  
TING GAO ◽  
FENGLI YAN ◽  
ZHIXI WANG
Keyword(s):  
Secure Communication ◽  
Secret Message ◽  
Quantum Channels ◽  
Classical Communication ◽  
Direct Communication ◽  
Classical Information ◽  
Epr Pairs ◽  
Unitary Transformations ◽  
Local Measurements ◽  
The Common

Two schemes for quantum secure conditional direct communication are proposed, where a set of EPR pairs of maximally entangled particles in Bell states, initially made by the supervisor Charlie, but shared by the sender Alice and the receiver Bob, functions as quantum information channels for faithful transmission. After insuring the security of the quantum channel and obtaining the permission of Charlie (i.e., Charlie is trustworthy and cooperative, which means the "conditional" in the two schemes), Alice and Bob begin their private communication under the control of Charlie. In the first scheme, Alice transmits secret message to Bob in a deterministic manner with the help of Charlie by means of Alice's local unitary transformations, both Alice and Bob's local measurements, and both of Alice and Charlie's public classical communication. In the second scheme, the secure communication between Alice and Bob can be achieved via public classical communication of Charlie and Alice, and the local measurements of both Alice and Bob. The common feature of these protocols is that the communications between two communication parties Alice and Bob depend on the agreement of the third side Charlie. Moreover, transmitting one bit secret message, the sender Alice only needs to apply a local operation on her one qubit and send one bit classical information. We also show that the two schemes are completely secure if quantum channels are perfect.

scholarly journals Thermodynamic Model for Energy-Constrained Open-System Evolution of Crustal Magma Bodies Undergoing Simultaneous Recharge, Assimilation and Crystallization: the Magma Chamber Simulator

2014 ◽  
Vol 55 (9) ◽  
pp. 1685-1717 ◽  
Author(s):  
Wendy A. Bohrson ◽  
Frank J. Spera ◽  
Mark S. Ghiorso ◽  
Guy A. Brown ◽  
Jeffrey B. Creamer ◽  
...  
Keyword(s):  
Magma Chamber ◽  
Open System ◽  
Thermodynamic Model ◽  
System Evolution ◽  
Energy Constrained ◽  
Crustal Magma

ENTROPY GROWTH INDUCED BY A SQUEEZED FIELD WITH A PHASE-DAMPING RESERVOIR

2009 ◽  
Vol 23 (25) ◽  
pp. 4993-5001
Author(s):  
A.-S. F. OBADA ◽  
H. A. HESSIAN ◽  
A.-B. A. MOHAMED
Keyword(s):  
Temporal Evolution ◽  
Single Mode ◽  
Initial Field ◽  
High Q ◽  
Phase Damping ◽  
Level Atom ◽  
Squeezed Coherent State ◽  
Entanglement Measures ◽  
Field State ◽  
Entropy Growth

A system of a two level atom interacting with a multi-photon single mode of electromagnetic field and damped with a phase reservoir is considered. The squeezed coherent state is taken as initial field state. The exact solution of the master equation in the case of a high-Q cavity is found. The effects of phase damping on the temporal evolution of some quantitative entanglement measures between the states of the system are investigated.

scholarly journals Experimental realization of a two-bit phase damping quantum code

1999 ◽  
Vol 60 (3) ◽  
pp. 1924-1943 ◽  
Author(s):  
Debbie Leung ◽  
Lieven Vandersypen ◽  
Xinlan Zhou ◽  
Mark Sherwood ◽  
Constantino Yannoni ◽  
...  
Keyword(s):  
Quantum Code ◽  
Experimental Realization ◽  
Phase Damping

Quantum feedback control for qubit-qutrit entanglement

2016 ◽  
Vol 16 (7&8) ◽  
pp. 597-614
Author(s):  
Tiantian Ma ◽  
Jun Jing ◽  
Yi Guo ◽  
Ting Yu
Keyword(s):  
Feedback Control ◽  
Open System ◽  
Control Mechanism ◽  
Initial State ◽  
Level Atom ◽  
Control Scheme ◽  
Quantum Feedback ◽  
Local Feedback ◽  
Quantum Open System ◽  
Different Parts

We study a hybrid quantum open system consisting of two interacting subsystems formed by one two-level atom (qubit) and one three-level atom (qutrit). The quantum open system is coupled to an external environment (cavity) via the qubit-cavity interaction. It is found that the feedback control on different parts of the system (qubit or qutrit) gives dramatically different asymptotical behaviors of the open system dynamics. We show that the local feedback control mechanism acting on the qutrit subsystem is superior than that on the qubit in the sense of improving the entanglement. Particularly, the qutrit-control scheme may result in an entangled steady state, depending on the initial state.

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