GAUGE THEORY AND TWO LEVEL SYSTEMS

被引：15
|
作者：
Bruno, A. [1 ,2 ,4 ]
Capolupo, A. [3 ]
Kak, S. [5 ]
Raimondo, G. [1 ,2 ]
Vitiello, G. [3 ,4 ]
机构：
[1] Univ Salerno, Dipartimento Fis ER Caianiello, I-84100 Salerno, Italy
[2] Univ Salerno, Ist Nazl Fis Nucl, I-84100 Salerno, Italy
[3] Univ Salerno, Dipartimento Matemat & Informat, I-84100 Salerno, Italy
[4] Ist Nazl Fis Nucl, Grp Collegato Salerno, I-84100 Salerno, Italy
[5] Oklahoma State Univ, Dept Comp Sci, Stillwater, OK 74078 USA
来源：
MODERN PHYSICS LETTERS B | 2011年 / 25卷 / 20期
关键词：
Gauge theory; qubit; Berry-like geometric phase; free energy; birefringence medium; QUANTUM-FIELD THEORY; NEUTRINO OSCILLATIONS;
D O I：
10.1142/S021798491102698X
中图分类号：
O59 [应用物理学];
学科分类号：
摘要：
We consider the time evolution of a two level system (a two level atom or a qubit) and show that it is characterized by a local (in time) gauge in variant evolution equation. The covariant derivative operator is constructed and related to the free energy. We show that the gauge invariant characterization of the time evolution of the two level system is analogous to the birefringence phenomenon in optics. The relation with Berry-like and Anandan-Aharonov phase is pointed out. Finally, we discuss entropy, environment effects and the distance in projective Hilbert space between two level states in their evolution.
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页码：1661 / 1670
页数：10
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