Two-Photon Dynamics in Coherent Rydberg Atomic Ensemble (original) (raw)
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Coherent Atom-Light Interactions in Rydberg Systems
2021
This thesis investigates the effects of strong Rydberg-Rydberg interactions in the presence of three-level coherent phenomena such as electromagnetically induced transparency (EIT), Autler-Townes splitting (ATS) and coherent population trapping (CPT). As a result of their remarkable properties, highly excited Rydberg atoms have great potential for applications in diverse areas. The interaction-induced dipole blockade between the Rydberg atoms has been proposed as a fundamental tool in quantum information processing with neutral atoms. Yet, they require an increasing level of understanding and control. A many-body theory is developed for the Rydberg excitation dynamics in various atomic systems with different densities and velocity distributions such as for atoms in a vapour cell, ultracold atoms in magneto-optical and optical dipole traps, or a system of optical lattices or dipole trap arrays. The systems were investigated by solving the optical Bloch equations numerically for a two...
Photon-photon interactions in Rydberg-atom arrays
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We investigate the interaction of weak light fields with two-dimensional lattices of atoms with high lying atomic Rydberg states. This system features different interactions that act on disparate length scales, from zero-range defect scattering of atomic excitations and finite-range dipole exchange processes to long-range Rydberg-state interactions, which span the entire array and can block multiple Rydberg excitations. Analyzing their interplay, we identify conditions that yield a nonlinear quantum mirror which coherently splits incident fields into correlated photon-pairs in a single transverse mode, while transmitting single photons unaffected. In particular, we find strong anti-bunching of the transmitted light with equal-time pair correlations that decrease exponentially with an increasing range of the Rydberg blockade. Such strong photon-photon interactions in the absence of photon losses open up promising avenues for the generation and manipulation of quantum light, and the e...
Cooperative Atom-Light Interaction in a Blockaded Rydberg Ensemble
Physical Review Letters, 2010
By coupling a probe transition to a Rydberg state using electromagnetically induced transparency (EIT) we map the strong dipole-dipole interactions onto an optical field. We characterize the resulting cooperative optical non-linearity as a function of probe strength and density. We show that the effect of dipole blockade cannot be described using a mean-field but requires an N-atom cooperative model. Good quantitative agreement is obtained for three atoms per blockade with the n = 60 Rydberg state. We place an upper-limit on the dephasing rate of the blockade spheres of < 110 kHz.
Photon-photon gate via the interaction between two collective Rydberg excitations
Physical Review A, 2015
We propose a scheme for a deterministic controlled-phase gate between two photons based on the strong interaction between two stationary collective Rydberg excitations in an atomic ensemble. The distance-dependent character of the interaction causes both a momentum displacement of the collective excitations and unwanted entanglement between them. We show that these effects can be overcome by swapping the collective excitations in space and by optimizing the geometry, resulting in a photon-photon gate with high fidelity and efficiency. arXiv:1407.7510v1 [quant-ph]
Coherent excitation of a single atom to a Rydberg state
Physical Review A, 2010
We present the coherent excitation of a single Rubidium atom to the Rydberg state 58d 3/2 using a two-photon transition. The experimental setup is described in detail, as well as experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between ground and Rydberg states of the atom. We analyze the observed oscillations in detail and compare them to numerical simulations which include imperfections of our experimental system. Strategies for future improvements on the coherent manipulation of a single atom in our settings are given.
Observation of collective excitation of two individual atoms in the Rydberg blockade regime
Nature Physics, 2009
When two quantum systems interact strongly with each other, their simultaneous excitation by the same driving pulse may be forbidden. The phenomenon is known as blockade of excitation. Recently, extensive studies have been devoted to the so-called Rydberg blockade between neutral atoms, which appears when the atoms are in highly excited electronic states, owing to the interaction induced by the accompanying large dipole moments. Rydberg blockade has been proposed as a basic tool in quantum-information processing with neutral atoms 1-5 , and can be used to deterministically generate entanglement of several atoms. Here, we demonstrate Rydberg blockade between two atoms individually trapped in optical tweezers at a distance of 4 µm. Moreover, we show experimentally that collective two-atom behaviour, associated with the excitation of an entangled state between the ground and Rydberg levels, enhances the allowed single-atom excitation. These observations should be a crucial step towards the deterministic manipulation of entanglement of two or more atoms, with possible implications for quantum-information science, as well as for quantum metrology, the study of strongly correlated systems in many-body physics, and fundamental studies in quantum physics.
Chirped pulse excitation of two-atom Rydberg states
Journal of Physics B Atomic Molecular and Optical Physics
We analyze excitation of two ground state atoms to a double Rydberg state by a two-photon chirped optical pulse in the regime of adiabatic rapid passage. For intermediate Rydberg-Rydberg interaction strengths, relevant for atoms separated by sim\simsimten mu\mumum, adiabatic excitation can be achieved at experimentally feasible Rabi frequencies and chirp rates of the pulses, resulting in high transfer efficiencies. We also study the adiabatic transfer between ground and Rydberg states as a means to realize a controlled phase gate between atomic qubits.
Three-photon electromagnetically induced transparency using Rydberg states
2014
We demonstrate electromagnetically induced transparency (EIT) in a four-level cascade system where the upper level is a Rydberg state. The observed spectral features are sub-Doppler and can be enhanced due to the compensation of Doppler shifts with AC Stark shifts. A theoretical description of the system is developed which agrees well with the experimental results and an expression for the optimum parameters is derived.
arXiv (Cornell University), 2018
We study optical bistable behavior of a Rydberg electromagnetically-induced transparency (EIT) atomic medium in a unidirectional optical ring-cavity. Due to strong van del Waal (vdW) interactions between the atoms, both optical nonlinear dispersion and nonlinear absorption coefficients are enhanced substantially. Under the condition of two-photon on resonance, we show that probe one-photon detuning can change the phase of the third order nonlinearity coefficient, which tunes the character of the optical bistability within different ratios of dispersive and absorptive types. This enables the single-photon control over photonic devices for further manipulation of light other than switches and transistors. More interestingly, we predict appearance of a scaling phenomena for optical bistabilities with the factors of coupling Rabi frequency and atomic density. Additionally, we also discuss the influence of the cavity detuning and the mirror transmission coefficient on the optical bistable behavior. The strong bistable feature provides a good ingredient for realizing all-optical logic gate devices in optical computing.
Quantum Gates and Multiparticle Entanglement by Rydberg Excitation Blockade and Adiabatic Passage
Physical Review Letters, 2008
We propose to apply stimulated adiabatic passage to transfer atoms from their ground state into Rydberg excited states. Atoms a few micrometers apart experience a dipole-dipole interaction among Rydberg states that is strong enough to shift the atomic resonance and inhibit excitation of more than a single atom. We show that the adiabatic passage in the presence of this interaction between two atoms leads to robust creation of maximally entangled states and to two-bit quantum gates. For many atoms, the excitation blockade leads to an effective implementation of collectivespin and Jaynes-Cummings-like Hamiltonians, and we show that the adiabatic passage can be used to generate collective Jx = 0 eigenstates and Greenberger-Horne-Zeilinger states of tens of atoms.