Cold Rydberg atoms are a useful medium to study physical properties for several reasons.The trapped and cooled atoms move on the order of 0.24 µm/µs -essentially stationary on the timescale of our experiments.In addition Rydberg Rubidium atoms have one loosely bound electron at a distance from the ion core ∝ n 2 .When a dressing field is applied to that electron, it oscillates between states creating a single atom dipole which is a useful object of study.This thesis presents experimental studies of dressed state Rydberg atoms.It was found that the dressed state is highly sensitive to the polarization of the dressing field.We characterized dressed state cold Rydberg atoms -how they behave under changes in dressing frequency, dressing power, polarization of dressing and probe fields, and density.i
Cold Rydberg atoms are a useful medium to study physical properties for several reasons.The trapped and cooled atoms move on the order of 0.24 µm/µs -essentially stationary on the timescale of our experiments.In addition Rydberg Rubidium atoms have one loosely bound electron at a distance from the ion core ∝ n 2 .When a dressing field is applied to that electron, it oscillates between states creating a single atom dipole which is a useful object of study.This thesis presents experimental studies of dressed state Rydberg atoms.It was found that the dressed state is highly sensitive to the polarization of the dressing field.We characterized dressed state cold Rydberg atoms -how they behave under changes in dressing frequency, dressing power, polarization of dressing and probe fields, and density.i
I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii This thesis reports the first observation of the resonant electric dipole-dipole interaction between cold Rydberg atoms using microwave spectroscopy, the observation of the magnetic field suppression of resonant interactions, and the development of a unique technique for precise magnetic field measurements. ARydbergstate(46d 5/2) of laser cooled 85 Rb atoms has been optically excited. A fraction of these atoms has been transferred to another Rydberg state (47p 3/2 or 45f 5/2,7/2) to introduce resonant electric dipole-dipole interactions. The line broadening of the two-photon 46d 5/2 − 47d 5/2 microwave transition due to the interaction of 46d 5/2 with 47p 3/2 or 45f 5/2,7/2 atoms has been used as a probe of the interatomic interactions. This experiment has been repeated with a DC magnetic field applied. The application of a weak magnetic field ( ≤ 0.6 G) has reduced
Advances in the coherent control of Rydberg atoms have led to an explosion in their use in a wide range of topics, including quantum computation, simulation, sensing, and networking. More specifically, Rydberg-coupled ensembles of atoms interfaced with a single mode of light have enabled studies of fundamental light-matter interactions at the single-photon level and have emerged as a promising platform to realize scalable quantum networking nodes. In the first part of this thesis, we utilize Rydberg blockade to generate large ensembles that host a single Rydberg excitation and use the collective state as a resource to efficiently generate single photons. We further investigate the shelving of the collective Rydberg excitations to the ground-state manifold, where we observe an order of magnitude increase in the coherence time of the excitation. In the latter half of the thesis, we use near-resonant microwave fields to generate microwave-dressed Rydberg states, where we utilize the degrees of freedom of the microwave field to tune the strength, form, and angular dependence of the dipole-dipole interactions. To this end, we develop a robust and highly tunable microwave polarization control system. We use a set of in-vacuum electrodes as microwave antennas. We measure the microwave polarizations produced by each source at the positions of the atoms using a Rydberg EIT-based polarimetry technique. By characterizing the three imperfect sources, we find the control settings necessary to produce \sigma_-, \pi, and \sigma_+ polarized microwaves with >99 % fidelity. We extend our purification techniques to frequencies away from Rydberg resonances by utilizing an auxiliary microwave field, generating two-photon microwave resonances. The high-fidelity microwave polarizations are used to resonantly admix opposite-parity Rydberg states, generating dressed states with dipole-dipole interactions that are longer range and stronger than the bare van der Waals interactions. To characterize the strength of the interactions, we measure the photon-number statistics of the light generated by the ensemble of atoms. By varying the cloud length relative to the blockade radii, we demonstrate a clear enhancement of the interaction strength due to microwave dressing. Our platform enables further engineering of interactions by exploiting the polarization and frequency degrees of freedom of the microwave fields, opening pathways for new quantum control strategies in many different experimental platforms.
In this thesis, we examine the ponderomotive interaction between an applied optical field and a highly excited Rydberg electron. An atom in a Rydberg state is essentially composed of an electron loosely bound, at a relatively large radial separation, to a positive ionic core. As such, the ponderomotive interaction for the Rydberg electron is similar to the interaction with free charges, which has been studied in context of plasma physics, new particle accelerator techniques, ion trapping, and electron diffraction among others. We are focused on using the ponderomotive interaction with the Rydberg electron to exert control over both the center-of-mass and electronic states of translationally cold Rydberg atoms. These capabilities can be adapted as tools for application in many experiments in areas such as atomic spectroscopy and quantum information processing. Our theoretical investigations have provided a well-defined parameter space for our experimental work and have allowed us to develop experimental methods appropriate for studying Rydberg atoms in ponderomotive potentials. In dense gases of cold Rydberg atoms, rich dynamics stem from electric multipole interactions among the Rydberg atoms. For example, interatomic forces between Rydberg atoms cause state-changing collisions which can significantly increase the kinetic energy of the colliding atoms. In addition to the studies of Rydberg atoms in ponderomotive potentials, we discuss collisions of cold Rydberg atoms in which internal energy of the Rydberg atoms is converted into kinetic energy.
Trapped Rydberg ions are a promising new platform for quantum computation and simulation. They combine the exquisite control of trapped ion systems with the strong dipole-dipole interactions available in Rydberg atom systems. In order to realize strong interactions between Rydberg ions, microwave dressing is required to induce strong oscillating dipoles. Additionally, microwave dressing of Rydberg states with polarizabilities of opposite sign allows for the realization of Rydberg states with vanishing polarizability. Such states are insensitive to external electric fields and can be trapped independently of their state. Vanishing-polarizability Rydberg states allow for implementing Rydberg entangling gates in large ion crystals.
Atoms in highly excited (Rydberg) states have a number of unique properties which make them attractive for applications in quantum information.These are large dipole moments, lifetimes and polarizabilities, as well as strong long-range interactions between Rydberg atoms.Experimental methods of laser cooling and precision spectroscopy enable the trapping and manipulation of single Rydberg atoms and applying them for practical implementation of quantum gates over qubits of a quantum computer based on single neutral atoms in optical traps.In this paper, we give a review of the experimental and theoretical work performed by the authors at the Rzhanov Institute of Semiconductor Physics SB RAS and Novosibirsk State University on laser and microwave spectroscopy of cold Rb Rydberg atoms in a magneto-optical trap and on their possible applications in quantum information.We also give a brief review of studies done by other groups in this area.
Atoms in highly excited (Rydberg) states have a number of unique properties which make them attractive for applications in quantum information. These are large dipole moments, lifetimes and polarizabilities, as well as strong long-range interactions between Rydberg atoms. Experimental methods of laser cooling and precision spectroscopy enable the trapping and manipulation of single Rydberg atoms and applying them for practical implementation of quantum gates over qubits of a quantum computer based on single neutral atoms in optical traps. In this paper, we give a review of the experimental and theoretical work performed by the authors at the Rzhanov Institute of Semiconductor Physics SB RAS and Novosibirsk State University on laser and microwave spectroscopy of cold Rb Rydberg atoms in a magneto-optical trap and on their possible applications in quantum information. We also give a brief review of studies done by other groups in this area.