Full Record

Author | Sete, Eyob Alebachew |

Title | Quantum Coherence Effects in Novel Quantum Optical Systems |

URL | http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400 |

Publication Date | 2012 |

Date Accessioned | 2012-10-22 18:00:12 |

Degree | PhD |

Discipline/Department | Physics |

Degree Level | doctoral |

University/Publisher | Texas A&M University |

Abstract | Optical response of an active medium can substantially be modified when coherent superpositions of states are excited, that is, when systems display quantum coherence and interference. This has led to fascinating applications in atomic and molecular systems. Examples include coherent population trapping, lasing without inversion, electromagnetically induced transparency, cooperative spontaneous emission, and quantum entanglement. We study quantum coherence effects in several quantum optical systems and find interesting applications. We show that quantum coherence can lead to transient Raman lasing and lasing without inversion in short wavelength spectral regions – extreme ultraviolet and x-ray – without the requirement of incoherent pumping. For example, we demonstrate transient Raman lasing at 58.4 nm in Helium atom and transient lasing without inversion at 6.1 nm in Helium-like Boron (triply-ionized Boron). We also investigate dynamical properties of a collective superradiant state prepared by absorption of a single photon when the size of the sample is larger than the radiation wavelength. We show that for large number of atoms such a state, to a good approximation, decays exponentially with a rate proportional to the number of atoms. We also find that the collective frequency shift resulting from repeated emission and reabsorption of short-lived virtual photons is proportional to the number of species in the sample. Furthermore, we examine how a position-dependent excitation phase affects the evolution of entanglement between two dipole-coupled qubits. It turns out that the coherence induced by position-dependent excitation phase slows down the otherwise fast decay of the two-qubit entanglement. We also show that it is possible to entangle two spatially separated and uncoupled qubits via interaction with correlated photons in a cavity quantum electrodynamics setup. Finally, we analyze how quantum coherence can be used to generate continuous-variable entanglement in quantum-beat lasers in steady state and propose possible implementation in quantum lithography. |

Subjects/Keywords | Quantum coherence effects; extreme ultraviolet and x-ray lasers; transient lasing without inversion; transient Raman lasing; superradiance; Collective Lamb (frequency) shift; dipole-coupled qubit entanglement; light-to-matter entanglement transfer; quantum beat laser; continuous-variable entanglement; quantum lithography |

Contributors | Scully, Marlan O. (advisor); Zubairy, Muhammad S. (committee member); Kocharovskaya, Olga (committee member); Chen, Goong (committee member) |

Language | en |

Country of Publication | us |

Record ID | handle:1969.1/ETD-TAMU-2012-08-11400 |

Repository | tamu |

Date Indexed | 2020-08-12 |

Grantor | Texas A&M University |

Issued Date | 2012-10-19 00:00:00 |

Sample Search Hits | Sample Images

…of emitted radiation. In this limit, |B0 ⟩
state is coupled to degenerate states |B1 ⟩ and |B2 ⟩. . . . . . . . . . .
51
Relevant Dicke states for calculation of collective *Lamb* *shift* in
single photon Dicke superradiance. The solid arrows describe…

…Hamiltonian [Eq. (3.37)]. . . . . . . . . . . . . . . . . . .
57
Energy level diagram for two two-level atoms in bare basis (a) and
in the timed Dicke basis (b). The frequency *shift* ∆ = Ω12 cos φ
occurs as a result of…

…entering
ports A and B. Here DM is a dichroic mirror, OFM is optical
frequency modulator, BS is symmetric lossless beam splitter, and
M represents the mirrors. Upper arm of the interferometer experiences a phase *shift* 2φ at the phase shifter (PS)…

…before both
branches interfere on the substrate S. . . . . . . . . . . . . . . . . . . 111
43
Plots of the exposure dosage versus path-diﬀerence phase *shift* for
γ/Γ = 1, κ/Γ = 0.8, A/γ = 2, α = 0, N = 0.1, η = 0, and for
ϕ = 0 (red dotted curve…

…of an atom by absorbing a photon. These
energy nonconserving processes occur due to emission and reabsorption of short-lived
virtual photons. These processes are particularly important in calculating frequency
(*Lamb*) shifts and will be…