A short review of the theoretical studies of the cold atom micromaser (mazer) is presented. Existing models are then improved by considering more general working conditions. Especially, the mazer physics is investigated in the situation where a detuning between the cavity mode and the atomic transition frequency is present. Interesting new effects are pointed out. Especially, it is shown that the cavity may slow down or speed up the atoms according to the sign of the detuning and that the induced emission process may be completely blocked by use of a positive detuning. The transmission probability of ultracold atoms through a micromaser is also studied and we generalize previous results established in the resonant case. In particular, it is shown that the velocity selection of cold atoms passing through the micromaser can be very easily tuned and enhanced using a nonresonant field inside the cavity. This manuscript is a summary of Martin's master thesis and articles [Phys. Rev. A 67, 053804 (2003)] and [Eur. Phys. J. D 29, 133 (2004)].
We refute in this Reply the criticisms made by M. Abdel-Aty [Phys. Rev. A 70, 047801 (2004)]. We show that none of them are founded and we demonstrate very explicitly what is wrong in the arguments developed by this author.
In a recent work, Bastin and Martin (B-M) [Phys. Rev. A 67, 053804 (2003)] have analyzed the quantum theory of the mazer in the off-resonant case. However, our analysis of this case refutes their claim by showing that their evaluation of the coupled equations for the off-resonant case is not satisfactory. The correct expression can be obtained by applying an appropriate formulae for the involved dressed-state parameters.
The quantum theory of the mazer in the non-resonant case (a detuning between the cavity mode and the atomic transition frequencies is present) is written. The generalization from the resonant case is far from being direct. Interesting effects of the mazer physics are pointed out. In particular, it is shown that the cavity may slow down or speed up the atoms according to the sign of the detuning and that the induced emission process may be completely blocked by use of a positive detuning. It is also shown that the detuning adds a potential step effect not present at resonance and that the use o…
The transmission probability of ultracold atoms through a micromaser is studied in the general case where a detuning between the cavity mode and the atomic transition frequencies is present. We generalize previous results established in the resonant case (zero detuning) for the mesa mode function. In particular, it is shown that the velocity selection of cold atoms passing through the micromaser can be very easily tuned and enhanced using a non-resonant field inside the cavity. Also, the transmission probability exhibits with respect to the detuning very sharp resonances that could define sing…
The quantum theory of the cold atom micromaser including the effects of gravity is established in the general case where the cavity mode and the atomic transition frequencies are detuned. We show that atoms which classically would not reach the interaction region are able to emit a photon inside the cavity. The system turns out to be extremely sensitive to the detuning and in particular to its sign. A method to solve the equations of motion for non resonant atom-field interaction and arbitrary cavity modes is presented.
We investigate exciton emission of quantum well embedded in a semiconductor microcavity. The analytical expressions of the light intensity for the cases of excitonic number state and coherent state are presented by using secular approximation. Our results show that the effective exciton-exciton interaction leads to the appearance of collapse and revival of the light intensity. The revival time is twice compared the coherent state case with that of the number state. The dissipation of the exciton-polariton lowers the revival amplitude but does not alter the revival time. The influences of the d…
The non-resonant interaction between the high-density excitons in a quantum well and a single mode cavity field is investigated. An analytical expression for the physical spectrum of the excitons is obtained. The spectral properties of the excitons, which are initially prepared in the number states or the superposed states of the two different number states by the resonant femtosecond pulse pumping experiment, are studied. Numerical study of the physical spectrum is carried out and a discussion of the detuning effect is presented.
We examine the competition among one- and two-photon processes in an ultra-cold, three-level atom undergoing cascade transitions as a result of its interaction with a bimodal cavity. We show parameter domains where two-photon transitions are dominant and also study the effect of two-photon emission on the mazer action in the cavity. The two-photon emission leads to the loss of detailed balance and therefore we obtain the photon statistics of the cavity field by the numerical integration of the master equation. The photon distribution in each cavity mode exhibits sub- and super- Poissonian beha…
We study several extensions of the single-photon, cavity-mediated quantum logical gates recently proposed by Koshino, Ishizaka and Nakamura: to a double-sided cavity configuration, to the case where the two atomic ground states are nondegenerate, and to include nonadiabatic corrections. Our analysis can be used to estimate the effects of various imperfections, and to prepare the way for a proof-of-principle demonstration with present technology. An interesting result is that the leading correction to the adiabatic approximation can be made to vanish for a suitable choice of detunings, provided…
Characteristic dips appear in the coherence traces of a probe qubit when dynamical decoupling (DD) is applied in synchrony with the precession of target nuclear spins, forming the basis for nanoscale nuclear magnetic resonance (NMR). The frequency of the microwave control pulses is chosen to match the qubit transition but this can be detuned from resonance by experimental errors, hyperfine coupling intrinsic to the qubit, or inhomogeneous broadening. The detuning acts as an additional static field which is generally assumed to be completely removed in Hahn echo and DD experiments. Here we demo…
Non-Hermitian, tight-binding $\mathcal{PT}$-symmetric models are extensively studied in the literature. Here, we investigate two forms of non-Hermitian Hamiltonians to study the $\mathcal{PT}$-symmetry breaking thresholds and features of corresponding surfaces of exceptional points (EPs). They include one-dimensional chains with uniform or 2-periodic tunnelling amplitudes, one pair of balanced gain and loss potentials $Δ\pmıγ$ at parity-symmetric sites, and periodic or open boundary conditions. By introducing a Hermitian detuning potential, we obtain the dependence of the $\mathcal{PT}$-thresh…
The interaction of a quantized field with three-level atoms in $Λ$ configuration inside a two-mode cavity is analyzed in the small noise approximation. The atoms are in a two-photon detuning with respect to the carriers of the field. We calculate the stationary quadrature noise spectrum of the field outside the cavity in the case where the input probe field is a squeezed state and the input pump field is a coherent state. The mean value of the field is unaltered in all the analysis: the atoms shows electromagnetically induced transparency (EIT). The effect of the atoms' base level decoherence …
In this paper, we follow our presented model in J. Opt. Soc. Am. B {\bf 30}, 1109--1117 (2013), in which the interaction between a $Λ$-type three-level atom and a quantized two-mode radiation field in a cavity in the presence of nonlinearities is studied. After giving a brief review on the procedure of obtaining the state vector of the atom-field system, some further interesting and important physical features (which are of particular interest in the quantum optics field of research) of the whole system state, i.e., the number-phase entropic uncertainty relation (based on the two-mode Pegg-Bar…
In this paper, we investigate the possibility of the entanglement swapping between two independent nonperfect cavities consisting of an atom with finite lifetime of atomic levels (as two independent sources of dissipation) which interacts with a quantized electromagnetic field in the presence of detuning and Kerr medium. In fact, there is no direct interaction between the two atoms, therefore, no entanglement exists between them. We use the Bell state measurement performing on the photons leaving the cavities to swap the entanglement stored between the atom-fields in each cavity into atom-atom…
The coherent evolution of the atom-cavity state in bimodal (cavity) experiments has been analyzed for a realistic time-dependence in detuning the atomic transition frequency. Apart from a `smooth switch' of the atomic resonance from one to the second mode of a bimodal cavity, we considered also an additional (effective) interaction between the field modes of the cavity, known as `communication channel'. Comparison of our model computations has been made especially with the measurements by Rauschenbeutel et al., [2001 Phys. Rev. A 64 050301] who demonstrated for the first time the entanglement …
We investigate the quantum Zeno and anti-Zeno effects on pairwise entanglement dynamics of a collective of non-interacting qubits which have been initially prepared in a Werner state and are off-resonantly coupled to a common and non-Markovian environment. We obtain the analytical expression of the concurrence in the absence and presence of the non-selective measurements. In particular, we express our results in the strong and weak coupling regimes and examine the role of the system size, and the effect of the detuning from the cavity field frequency on the temporal behaviour of the pairwise e…
We consider a semiconductor quantum well in a microcavity driven by coherent light and coupled to a squeezed vacuum reservoir. By systematically solving the pertinent quantum Langevin equations in the strong coupling and low excitation regimes, we study the effect of exciton-photon detuning, external coherent light, and the squeezed vacuum reservoir on vacuum Rabi splitting and on quantum statistical properties of the light emitted by the quantum well. We show that the exciton-photon detuning leads to a shift in polariton resonance frequencies and a decrease in fluorescence intensity. We also …
The entanglement between two atoms in a damping Jaynes-Cummings model is investigated with different decay coefficients of the atoms from the upper level to other levels under detuning between the atomic frequency and the quantized light field frequency. The results indicate that the larger the decay coefficient is, the more quickly the entanglement decays. The detuning enhances the entanglement's average value at long times. More importantly, the results show that the so-called sudden death effect can be avoided by enhancing the detuning or the decay coefficient.
We study evolution of entanglement of two two-level atoms placed inside a multilayered microsphere. We show that due to inhomogeneity of the field modes this entanglement essentially depends on the atomic positions (asymmetrical entanglement) and also on the detuning between the atomic transitions and field frequencies. The robust and complete entanglement can be achieved even in the resonant case when the atoms have different effective coupling constants, and it can be extended in time if the detuning is large enough. We study analytically the lossless case and estimate numerically the effect…
In this paper we study the production of entanglement between two atoms which are far from each other. We consider a system including eight two-level atoms (1; 2;... ; 8) such that any atom with its adjacent atom is in atomic Bell state, so that we have four separate pairs of maximally entangled states (i; i + 1) where i = 1; 3; 5; 7. Our purpose is to produce entanglement between the atomic pair (1, 8), while these two distant atoms have no interaction. By performing the interaction between adjacent nonentangled atomic pairs (2, 3) as well as (6, 7), each pair with a two-mode quantized field,…
Taking the non-Markovian effect into account, we study how to store a single photon of arbitrary temporal shape in a single atom coupled to an optical cavity. Our model applies to Raman transitions in three-level atoms with one branch of the transition controlled by a driving pulse, and the other coupled to the cavity. For any couplings of input field to the optical cavity and detunings of the atom from the driving pulse and cavity, we extend the input-output relation from Markovian dynamics to non-Markovian one. For most possible photon shapes, we derive an analytic expression for the driving…
In this paper I study the dynamics of a two-level atom interacting with a standing wave field. When the atom is subjected to a weak linear force, the problem can be turned into a time dependent one, and the evolution is understood from the band structure of the spectrum. The presence of level crossings in the spectrum gives rise to Bloch oscillations of the atomic motion. Here I investigate the effects of the atom-field detuning parameter. A variety of different level crossings are obtained by changing the magnitude of the detuning, and the behaviour of the atomic motion is strongly affected d…
The superfluid to Mott insulator transition in cavity polariton arrays is analyzed using the variational cluster approach, taking into account quantum fluctuations exactly on finite length scales. Phase diagrams in one and two dimensions exhibit important non-mean-field features. Single-particle excitation spectra in the Mott phase are dominated by particle and hole bands separated by a Mott gap. In contrast to Bose-Hubbard models, detuning allows for changing the nature of the bosonic particles from quasi-localized excitons to polaritons to weakly interacting photons. The Mott state with dens…
A single four-level atom interacting with two-mode cavities is investigated. Under large detuning condition, we obtain the effective Hamiltonian which is unitary squeezing operator of two-mode fields. Employing the input-output theory, we find that the entanglement and squeezing of the output fields can be achieved. By analyzing the squeezing spectrum, we show that asymmetric detuning and asymmetric atomic initial state split the squeezing spectrum from one valley into two minimum values, and appropriate leakage of the cavity is needed for obtaining output entangled fields.
The transmission spectrum of two dipole-dipole coupled atoms interacting with a single-mode optical cavity in strong coupling regime is investigated theoretically for the lower and higher excitation cases, respectively. The dressed states containing the dipole-dipole interaction (DDI) are obtained by transforming the two-atom system into an effective single-atom one. We found that the DDI can enhance the effects resulting from the positive atom-cavity detunings but weaken them for the negative detunings cases for lower excitation, which can promote the spectrum exhibiting two asymmetric peaks …
Quantum optimization with globally driven neutral atom arrays
University of Innsbruck（因斯布鲁克大学）；Parity Quantum Computing GmbH（Parity量子计算有限公司）；Digital Cardiology Lab, University Clinic of Internal Medicine III, Medical University of Innsbruck（因斯布鲁克医科大学第三内科大学诊所数字心脏病学实验室）；Parity Quantum Computing Germany GmbH（Parity量子计算德国有限公司）；Parity Quantum Computing France SAS（Parity量子计算法国股份公司）
We investigate the time evolution and asymptotic behavior of a system of two two-level atoms (qubits) interacting off-resonance with a single mode radiation field. The two atoms are coupled to each other through dipole-dipole as well as Ising interactions. An exact analytic solution for the system dynamics that spans the entire phase space is provided. We focus on initial states that cause the system to evolve to entanglement sudden death (ESD) between the two atoms. We find that combining the Ising and dipole-dipole interactions is very powerful in controlling the entanglement dynamics and ES…
We study the coupling between collective variables of atomic spin and light polarization in an ensemble of cold 87Rb probed with polarized light. The effects of multiple hyperfine levels manifest themselves as a rank-2 tensor polarizability, whose irreducible components can be selected by means of probe detuning. The D1 and D2 lines of Rb are explored and we identify different detunings which lead to Hamiltonians with different symmetries for rotations. As possible applications of these Hamiltonians, we describe schemes for spin squeezing, quantum cloning, quantum memory, and measuring atom nu…
We study the entanglement properties of two three-level Rydberg atoms passing through a single-mode cavity. The interaction of an atom with the cavity field allows the atom to make a transition from the upper most (lower most) to the lower most (upper most) level by emission (absoprtion) of two photons via the middle level. We employ an effective Hamiltonian that describes the system with a Stark shifted two-photon atomic transition. We compute the entanglement of formation of the joint two-atom state as a function of Rabi angle $gt$. It is shown that the Stark shift can be used to enhance the…
We consider a micromaser model to study the influence of Dicke superradiance in the context of the one-atom maser. The model involves a microwave cavity into which two-level Rydberg atoms are pumped in pairs. We consider a random pump mechanism which allows the presence of at most one pair of atoms in the cavity at any time. We analyze the differences between the present system, called the Dicke micromaser, and an equivalently pumped conventional one-atom micromaser. These differences are attributed to the Dicke cooperativity in the two-atom system. We also show that the two-atom Dicke microma…
We investigate how to describe the dissipative spin dynamics of the driven-dissipative Dicke model, describing $N$ two-level atoms coupled to a cavity mode, after adiabatic elimination of the cavity mode. To this end, we derive a Redfield master equation which goes beyond the standard secular approximation and large detuning limits. We show that the secular (or rotating wave) approximation and the large detuning approximation both lead to inadequate master equations, that fail to predict the Dicke transition or the damping rates of the atomic dynamics. In contrast, the full Redfield theory cor…
We propose a method to entangle two distant vibrating microsize mirrors (i.e., mechanical oscillators) in a cavity optomechanical system. In this scheme, we discuss both the resonant and large-detuning conditions, and show that the entanglement of two mechanical oscillators can be achieved with the assistance of a two-level atom and cavity-radiation pressure. In the resonant case, the operation time is relatively short, which is desirable to minimize the effects of decoherence. While in the large-detuning case, the cavity is only virtually excited during the interaction. Therefore, the decay o…
We study the quantum limits in an optomechanical sensor based on a detuned high-finesse cavity with a movable mirror. We show that the radiation pressure exerted on the mirror by the light in the detuned cavity induces a modification of the mirror dynamics and makes the mirror motion sensitive to the signal. This leads to an amplification of the signal by the mirror dynamics, and to an improvement of the sensor sensitivity beyond the standard quantum limit, up to an ultimate quantum limit only related to the mechanical dissipation of the mirror. This improvement is somewhat similar to the one …
The optical bistability (OB) in a two-mode optomechanical system with a Bose-Einstein condensate (BEC) is studied. By investigating the behavior of steady state solutions, we show that how OB develops in the system for a certain range of cavity-pump detunings and pump amplitudes. We then investigate the effects of the decay rate of the cavity photons and coupling strength between the cavity and the BEC as well as the pump-atom detuning on the optical behaviour of the system. We find that one can control the OB threshold and width of the bistability curve via adjusting properly the decay rate, …
A two-level system interacting with a cavity field is an important model for investigating the photon blockade (PB) effect. Most work on this topic has been based on the assumption that the atomic transition frequency is resonant with the fundamental mode frequency of the cavity. We relax this constraint and reexamine PB in a more general atom--cavity system with arbitrary atomic and cavity detunings from a driving field. The results show that when the signs of the atomic and cavity detunings are the same, PB occurs only in the strong-coupling regime, but for opposite signs of the atomic and c…
We study the motion of a cold atom in a frequency-modulated standing laser wave. If the detuning between the atomic electronic transition and the field is large, the atom moves in a modulated optical potential demonstrating known classical nonlinear effects such as chaos and nonlinear resonances. If the atom-field detuning is small, then two optical potentials emerge in the system, and the atom performs Landau-Zener (LZ) tunnelings between them. It is a radically non-classical behavior. However, we show that classical nonlinear structures in system's phase space (KAM-tori and chaotic layers) s…
High-Q microwave cavity modes coupled to transmon ancillas provide a hardware-efficient platform for quantum computing. Due to their coupling, the cavity modes inherit finite nonlinearity from the transmons. In this work, we theoretically and experimentally investigate how an off-resonant drive on the transmon ancilla modifies the nonlinearities of cavity modes in qualitatively different ways, depending on the interrelation among cavity-transmon detuning, drive-transmon detuning and transmon anharmonicity. For a cavity-transmon detuning that is smaller than or comparable to the drive-transmon …
The single photon transport through a one dimensional array of cavities is studied theoretically. Analytical expressions of the reflection and transmission are given. The transmission shows an energy spectrum with forbidden and allowed bands that depends on the detuning parameter of the system. We show that the allowed miniband is formed due to the indirect coupling between the atoms in each cavity. In addition, the band edges can be controlled by the degree of detuning of the level of the atoms. We discuss the analogy between this phenomenon with the Fano and Dicke effects.
The Coulomb repulsion between ions in a linear Paul trap give rise to anharmonic terms in the potential energy when expanded about the equilibrium positions. We examine the effect of these anharmonic terms on the accuracy of a quantum simulator made from trapped ions. To be concrete, we consider a linear chain of $\text{Yb}^{171+}$ ions stabilized close to the zigzag transition. We find that for typical experimental temperatures, frequencies change by no more than a factor of $0.01\%$ due to the anharmonic couplings. Furthermore, shifts in the effective spin-spin interactions (driven by a spin…
We theoretically investigate the optical second-order sideband generation (OSSG) in an optical parity-time (PT) symmetric system, which consists of a passive cavity trapping the atomic ensemble and an active cavity. It is found that near the exceptional point (EP), the efficiency of the OSSG increases sharply not only for the blue probe-pump detuning resonant case but also for the red one. Using experimentally achievable parameters, we study the effect of the atomic ensemble on the efficiency of the OSSG. The numerical results show that the efficiency of the OSSG is 30% higher than that of the…
In this work we demonstrate theoretically how to use external laser field to control the population inversion of a single quantum dot exciton qubit in a nanocavity. We consider the Jaynes-Cummings model to describe the system, and the incoherent losses were take into account by using Lindblad operators. We have demonstrated how to prepare the initial state in a superposition of the exciton in the ground state and the cavity in a coherent state. The effects of exciton-cavity detuning, the laser-cavity detunings, the pulse area and losses over the qubit dynamics are analyzed. We also show how to…
