Genuine vacuum-induced geometric phases

2015 ◽  
Vol 29 (11) ◽  
pp. 1550043 ◽  
Author(s):  
Minghao Wang ◽  
L. F. Wei ◽  
J. Q. Liang
Keyword(s):  
Excited State ◽  
Quantum Electrodynamics ◽  
Geometric Phase ◽  
Berry Phase ◽  
Cavity Quantum Electrodynamics ◽  
Vacuum Field ◽  
Geometric Phases ◽  
Field System ◽  
The One

Since a pioneer work on vacuum-induced Berry phase (VIBP) was done by Fuentes-Guridi et al. [Phys. Rev. Lett. 89 (2002) 220404], much attention has been paid to the geometric phase effects of vacuum field. However, all the so-called VIBPs investigated previously are not purely vacuum-induced (i.e. the nonvacuum components of the field are also involved). In this paper, we discuss how to deliver geometric phases from the evolution of a genuine vacuum field in a standard cavity quantum electrodynamics (QED) system. First, we design a cyclic evolution of an atom–field system with the atom being initially prepared at the excited state and the field at the genuine vacuum. Then, we calculate the geometric phases acquired during such a cyclic evolution. It is found that such geometric phases are really induced by an evolution of the genuine vacuum field. Specifically, our generic proposal is demonstrated with both the one- and two-mode Jaynes–Cummings model interactions (JCM).

BERRY PHASE IN COUPLED TWO-LEVEL SYSTEMS

2013 ◽  
Vol 27 (12) ◽  
pp. 1350088 ◽  
Author(s):  
X. Y. ZHANG ◽  
J. H. TENG ◽  
X. X. YI
Keyword(s):  
Asymptotic Behavior ◽  
Geometric Phase ◽  
Berry Phase ◽  
External Control ◽  
Control Parameters ◽  
Coupling Constant ◽  
Geometric Phases ◽  
Coupled Subsystems ◽  
Two Level Systems ◽  
The Individual

The application of geometric phases into robust control of quantal systems has triggered exploration of the geometric phase for coupled subsystems. Earlier studies have mainly focused on the situation where the external control parameters are in the free Hamiltonian of the subsystems, i.e. the controls exert only on the individual subsystems. Here we consider another circumstance that we can control the coupling geiϕ between the subsystems. By changing only the phase ϕ in the coupling constant, we derive the Berry phase acquired by the system and compare it to the geometric phase acquired by changing the coupling strength g. We find that the asymptotic behavior of the Berry phase depends on the relative Rabi frequency of the two subsystems, and it approaches π when the amplitude of the coupling tends to infinity.

scholarly journals Geometric phases for mixed states of the Kitaev chain

2016 ◽  
Vol 374 (2068) ◽  
pp. 20150231 ◽  
Author(s):  
Ole Andersson ◽  
Ingemar Bengtsson ◽  
Marie Ericsson ◽  
Erik Sjöqvist
Keyword(s):  
Finite Temperature ◽  
Geometric Phase ◽  
Berry Phase ◽  
Condensed Matter ◽  
Order Parameters ◽  
Topological Order ◽  
Mixed States ◽  
Geometric Phases

The Berry phase has found applications in building topological order parameters for certain condensed matter systems. The question whether some geometric phase for mixed states can serve the same purpose has been raised, and proposals are on the table. We analyse the intricate behaviour of Uhlmann's geometric phase in the Kitaev chain at finite temperature, and then argue that it captures quite different physics from that intended. We also analyse the behaviour of a geometric phase introduced in the context of interferometry. For the Kitaev chain, this phase closely mirrors that of the Berry phase, and we argue that it merits further investigation.

Quantum Radiation Field: Spontaneous Emission and Entangled Photons

2021 ◽  
pp. 247-273
Author(s):  
Duncan G. Steel
Keyword(s):  
Electromagnetic Field ◽  
Excited State ◽  
Radiation Field ◽  
Quantum Electrodynamics ◽  
Equations Of Motion ◽  
Single Mode ◽  
Vacuum Field ◽  
Level System ◽  
Quantum Radiation ◽  
System P

One of the greatest successes in quantum theory, and certainly one of the more important parts for application to devices and applications is the prediction of the emission of light through the quantization of an electromagnetic field. Broadly, this is the field of quantum electrodynamics. In this chapter, we develop the Hamiltonian for the classical electromagnetic field. It is seen that the Hamiltonian for each mode (identified by the k-vector and polarization of the field) of the plane wave electromagnetic field is identical to that of the harmonic oscillator. One unit of energy, ℏω, in a mode is a called a photon. The eigenkets for the system are number states (Fock states). We then consider a two-level system described by a Hamiltonian which couples the two-level quantum system to the quantized electromagnetic field. Using the Weisskopf–Wigner formalism developed in Chapter 14, we solve the equations of motion for the time dependent Schrödinger equation assuming the system starts in the excited state with no radiation present in the vacuum field. The results show the creation of one unit of energy in an electromagnetic mode corresponding to the emission of a photon. The excited state probability decays exponentially with the emission of this photon. We consider the important and special case of such a two-level system but in a cavity restricting the radiation field to a single mode. The Jaynes–Cummings Hamiltonian shows that this system, if started in the excited state, Rabi oscillates with no radiation incident on the system.

scholarly journals NON-MARKOVIAN DYNAMICS OF CAVITY LOSSES

2009 ◽  
Vol 07 (supp01) ◽  
pp. 41-47 ◽  
Author(s):  
MATTEO SCALA ◽  
BENEDETTO MILITELLO ◽  
ANTONINO MESSINA ◽  
JYRKI PIILO ◽  
SABRINA MANISCALCO ◽  
...  
Keyword(s):  
Excited State ◽  
Solid State ◽  
Master Equation ◽  
Quantum Electrodynamics ◽  
Cavity Quantum Electrodynamics ◽  
Markovian Dynamics ◽  
Microscopic Derivation ◽  
Recent Developments ◽  
Cavity System ◽  
Population Trapping

We provide a microscopic derivation for the non-Markovian master equation for an atom-cavity system with cavity losses and show that they can induce population trapping in the atomic excited state, when the environment outside the cavity has a non-flat spectrum. Our results apply to hybrid solid state systems and can turn out to be helpful to find the most appropriate description of leakage in the recent developments of cavity quantum electrodynamics.

scholarly journals Observation of twist-induced geometric phases and inhibition of optical tunneling via Aharonov-Bohm effects

2019 ◽  
Vol 5 (1) ◽  
pp. eaau8135 ◽  
Author(s):  
Midya Parto ◽  
Helena Lopez-Aviles ◽  
Jose E. Antonio-Lopez ◽  
Mercedeh Khajavikhan ◽  
Rodrigo Amezcua-Correa ◽  
...  
Keyword(s):  
Geometric Phase ◽  
Berry Phase ◽  
Polarization State ◽  
Guided Wave ◽  
Physical Sciences ◽  
Solid State Physics ◽  
Fiber System ◽  
Geometric Phases ◽  
Photon Tunneling ◽  
Aharonov Bohm

Geometric phases appear ubiquitously in many and diverse areas of the physical sciences, ranging from classical and molecular dynamics to quantum mechanics and solid-state physics. In the realm of optics, similar phenomena are known to emerge in the form of a Pancharatnam-Berry phase whenever the polarization state traces a closed contour on the Poincaré sphere. While this class of geometric phases has been extensively investigated in both free-space and guided wave systems, the observation of similar effects in photon tunneling arrangements has so far remained largely unexplored. Here, we experimentally demonstrate that the tunneling or coupling process in a twisted multicore fiber system can display a chiral geometric phase accumulation, analogous to the Aharonov-Bohm effect. In our experiments, the tunneling geometric phase is manifested through the interference of the corresponding supermodes. Our work provides the first observation of Aharonov-Bohm suppression of tunneling in an optical setting.

Investigate New Reactivities Enabled by Polariton Photochemistry

2019 ◽  
Author(s):  
Arkajit Mandal ◽  
Pengfei Huo
Keyword(s):  
Excited State ◽  
Quantum Electrodynamics ◽  
Quantum Dynamics ◽  
Optical Cavity ◽  
Cavity Quantum Electrodynamics ◽  
Photochemical Reactions ◽  
Isomerization Reaction ◽  
Resonance Case ◽  
Radiation Mode ◽  
Dynamics Simulations

We perform quantum dynamics simulations to investigate new chemical reactivities enabled by cavity quantum electrodynamics. The quantum light-matter interactions between the molecule and the quantized radiation mode inside an optical cavity create a set of hybridized electronic-photonic states, so-called polaritons. The polaritonic states adapt the curvatures from both the ground and the excited electronic states, opening up new possibilities to control photochemical reactions by exploiting intrinsic quantum behaviors of light-matter interactions. With direct quantum dynamics simulations, we demonstrate that the selectivity of a model photo-isomerization reaction can be controlled by tuning the photon frequency of the cavity mode or the light-matter coupling strength, providing new ways to manipulate chemical reactions via light-matter interaction. We further investigate collective quantum effects enabled by coupling quantized radiation mode to multiple molecules. Our results suggest that in the resonance case, a photon is recycled among molecules to enable multiple excited state reactions, thus effectively functioning as a catalyst. In the non-resonance case, molecules emit and absorb virtual photons to initiate excited state reactions through fundamental quantum electrodynamics processes. These results from direct quantum dynamics simulations reveal basic principles of polariton photochemistry as well as promising reactivities that take advantage of intrinsic quantum behaviors of photons.

scholarly journals Geometric phase for Dirac Hamiltonian under gravitational fields in the nonrelativistic regime

2021 ◽  
pp. 2150090
Author(s):  
Tanuman Ghosh ◽  
Banibrata Mukhopadhyay
Keyword(s):  
Black Hole ◽  
Geometric Phase ◽  
Berry Phase ◽  
Nonrelativistic Limit ◽  
Gravitational Fields ◽  
Schwarzschild Geometry ◽  
Bohm Effect ◽  
The One ◽  
Aharonov Bohm ◽  
Dirac Hamiltonian

We show the appearance of geometric phase in a Dirac particle traversing in nonrelativistic limit in a time-independent gravitational field. This turns out to be similar to the one originally described as a geometric phase in magnetic fields. We explore the geometric phase in the Kerr and Schwarzschild geometries, which have significant astrophysical implications. Nevertheless, the work can be extended to any spacetime background including that of time-dependent. In the Kerr background, i.e. around a rotating black hole, geometric phase reveals both the Aharonov–Bohm effect and Pancharatnam–Berry phase. However, in a Schwarzschild geometry, i.e. around a nonrotating black hole, only the latter emerges. We expect that our assertions can be validated in both the strong gravity scenarios, like the spacetime around black holes, and weak gravity environment around Earth.

Investigate New Reactivities Enabled by Polariton Photochemistry

2019 ◽  
Author(s):  
Arkajit Mandal ◽  
Pengfei Huo
Keyword(s):  
Excited State ◽  
Quantum Electrodynamics ◽  
Quantum Dynamics ◽  
Optical Cavity ◽  
Cavity Quantum Electrodynamics ◽  
Photochemical Reactions ◽  
Isomerization Reaction ◽  
Resonance Case ◽  
Radiation Mode ◽  
Dynamics Simulations

We perform quantum dynamics simulations to investigate new chemical reactivities enabled by cavity quantum electrodynamics. The quantum light-matter interactions between the molecule and the quantized radiation mode inside an optical cavity create a set of hybridized electronic-photonic states, so-called polaritons. The polaritonic states adapt the curvatures from both the ground and the excited electronic states, opening up new possibilities to control photochemical reactions by exploiting intrinsic quantum behaviors of light-matter interactions. With direct quantum dynamics simulations, we demonstrate that the selectivity of a model photo-isomerization reaction can be controlled by tuning the photon frequency of the cavity mode or the light-matter coupling strength, providing new ways to manipulate chemical reactions via light-matter interaction. We further investigate collective quantum effects enabled by coupling quantized radiation mode to multiple molecules. Our results suggest that in the resonance case, a photon is recycled among molecules to enable multiple excited state reactions, thus effectively functioning as a catalyst. In the non-resonance case, molecules emit and absorb virtual photons to initiate excited state reactions through fundamental quantum electrodynamics processes. These results from direct quantum dynamics simulations reveal basic principles of polariton photochemistry as well as promising reactivities that take advantage of intrinsic quantum behaviors of photons.

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