The electro-optic effect, where the refractive index of a medium is modified by an electric field... more The electro-optic effect, where the refractive index of a medium is modified by an electric field, is of central importance in nonlinear optics, laser technology, quantum optics and optical communications. In general, electro-optic coefficients are very weak and a medium with a giant electro-optic coefficient could have profound implications for precision electrometry and nonlinear optics at the single-photon level. Here we propose and demonstrate a giant d.c. electro-optic effect on the basis of polarizable (Rydberg) dark states. When a medium is prepared in a dark state consisting of a superposition of ground and Rydberg energy levels, it becomes transparent and acquires a refractive index that is dependent on the energy of the highly polarizable Rydberg state. We demonstrate phase modulation of the light field in the Rydberg-dark-state medium and measure an electro-optic coefficient that is more than six orders of magnitude larger than in usual Kerr media.
We report on a method of light-shift engineering where an auxiliary laser is used to tune the ato... more We report on a method of light-shift engineering where an auxiliary laser is used to tune the atomic transition frequency. The technique is used to selectively load a specific region of an optical lattice. The results are explained by calculating the differential light-shift of each hyperfine state. We conclude that the remarkable spatial selectivity of light-shift engineering using an auxiliary laser provides a powerful technique to prepare ultra-cold trapped atoms for experiments on quantum gases and quantum information processing.
By coupling a probe transition to a Rydberg state using electro-magnetically induced transparency... more By coupling a probe transition to a Rydberg state using electro-magnetically 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.
Journal of Physics B-atomic Molecular and Optical Physics, 2011
We study electromagnetically induced transparency (EIT) in the 5s$\rightarrow$5p$\rightarrow$46s ... more We study electromagnetically induced transparency (EIT) in the 5s$\rightarrow$5p$\rightarrow$46s ladder system of a cold $^{87}$Rb gas. We show that the resonant microwave coupling between the 46s and 45p states leads to an Autler-Townes splitting of the EIT resonance. This splitting can be employed to vary the group index by $\pm 10^5$ allowing independent control of the propagation of dark state polaritons. We also demonstrate that microwave dressing leads to enhanced interaction effects. In particular, we present evidence for a $1/R^3$ energy shift between Rydberg states resonantly coupled by the microwave field and the ensuing breakdown of the pair-wise interaction approximation.
We demonstrate a cooperative optical non-linearity caused by dipolar interactions between Rydberg... more We demonstrate a cooperative optical non-linearity caused by dipolar interactions between Rydberg atoms in an ultra-cold atomic ensemble. By coupling a probe transition to the Rydberg state we map the strong dipole-dipole interactions between Rydberg pairs onto the optical field. We characterize the non-linearity as a function of electric field and density, and demonstrate the enhancement of the optical non-linearity due to cooperativity.
Journal of Physics B-atomic Molecular and Optical Physics, 2008
We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas.... more We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas. We show that the onset of interactions is manifest as a depopulation of the Rydberg state and numerically model this effect by adding a density-dependent non-linear term to the optical Bloch equations. In the limit of a weak probe where the depopulation effect is negligible, we observe no evidence of interaction induced decoherence and obtain a narrow Rydberg dark resonance with a linewidth of <600 kHz, limited by the Rabi frequency of the coupling beam
We present a viewport for use in Ultra-high vacuum (UHV) based upon the preflattened solder seal ... more We present a viewport for use in Ultra-high vacuum (UHV) based upon the preflattened solder seal design presented in earlier work, Cox et al. Rev. Sci. Inst. 74, 3185 (2003). The design features significant modifications to improve long term performance. The windows have been leak tested to less than 10^-10 atm cm^3/s . From atom number measurements in an optical dipole trap loaded from a vapor cell magneto-optical trap (MOT) inside a vacuum chamber accommodating these viewports, we measure a trap lifetime of 9.5s suggesting a pressure of around 10^-10 Torr limited by background Rubidium vapor pressure. We also present a simplified design where the UHV seal is made directly to a vacuum pipe
Journal of Physics B-atomic Molecular and Optical Physics, 2009
We study the effect of a control beam on a Lambda electromagnetically induced transparency (EIT) ... more We study the effect of a control beam on a Lambda electromagnetically induced transparency (EIT) system in 87Rb. The control beam couples one ground state to another excited state forming a four level N-system. Phase coherent beams to drive the N-system are produced using a double injection scheme. We show that the control beam can be used to Stark shift or split the EIT resonance. Finally, we show that the when the control beam is on-resonance one observes a Doppler-free and sub-natural absorptive resonance with a width of order 100 kHz. Crucially, this narrow absorptive resonance only occurs when atoms with a range of velocities are present, as is the case in a room temperature vapour.
We present a design for a switchable nanomagnetic atom mirror formed by an array of 180° domain w... more We present a design for a switchable nanomagnetic atom mirror formed by an array of 180° domain walls confined within Ni80Fe20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror. We then describe the fabrication of a nanowire array and characterize its magnetic behavior using magneto-optic Kerr effect magnetometry, scanning Hall probe microscopy, and micromagnetic simulations, demonstrating how the mobility of the domain walls allow the atom mirror to be switched ``on'' and ``off'' in a manner which would be impossible for conventional designs. Finally, we model the reflection of 87Rb atoms from the atom mirror's surface, showing that our design is well suited for investigating interactions between domain walls and cold atoms.
We present a design for a switchable nanomagnetic atom mirror formed by an array of 180{\deg} dom... more We present a design for a switchable nanomagnetic atom mirror formed by an array of 180{\deg} domain walls confined within Ni80Fe20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror. We then describe the fabrication of a nanowire array and characterize its magnetic behavior using magneto-optic Kerr effect magnetometry, scanning Hall probe microscopy and micromagnetic simulations, demonstrating how the mobility of the domain walls allow the atom mirror to be switched "on" and "off" in a manner which would be impossible for conventional designs. Finally, we model the reflection of 87Rb atoms from the atom mirror's surface, showing that our design is well suited for investigating interactions between domain walls and cold atoms.
By coupling a probe transition to a Rydberg state using electromagnetically induced transparency ... more 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 nonlinearity as a function of probe strength and density. We demonstrate good quantitative agreement between the experiment and an N-atom cooperative model for N ¼ 3 atoms per blockade sphere and the n ¼ 60 Rydberg state.
Abstract We present a design for a switchable nanomagnetic atom mirror formed by an array of 180 ... more Abstract We present a design for a switchable nanomagnetic atom mirror formed by an array of 180 domain walls confined within Ni 80 Fe 20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror.
Abstract We study electromagnetically induced transparency (EIT) in the 5s→ 5p→ 46s ladder system... more Abstract We study electromagnetically induced transparency (EIT) in the 5s→ 5p→ 46s ladder system of a cold 87Rb gas. We show that the resonant microwave coupling between the 46s and 45p states leads to an Autler–Townes splitting of the EIT resonance. This splitting can be employed to vary the group index by±105 allowing independent control of the propagation of dark state polaritons. We also demonstrate that microwave dressing leads to enhanced interaction effects.
Abstract. We study electromagnetically induced transparency (EIT) of a weakly interacting cold Ry... more Abstract. We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas. We show that for Rydberg states with principal quantum numbers in the range n= 19���26, the onset of interactions is manifest as a depopulation of the Rydberg state. In the limit of a weak probe where the depopulation effect is negligible, we observe no evidence of interaction-induced decoherence and obtain a narrow Rydberg dark resonance with a linewidth of< 600 kHz.
Abstract We use the technique of electromagnetically induced transparency (EIT) to probe the effe... more Abstract We use the technique of electromagnetically induced transparency (EIT) to probe the effect of attractive dipole–dipole interactions in a highly excited Rydberg gas. The transient character of the EIT response is investigated by rapidly scanning the probe laser through resonance. We characterize the resulting cooperative optical non-linearity as a function of probe strength, density and scan direction. For the 58D5/2 Rydberg state, an atom density of 1.
Abstract: We demonstrate a cooperative optical non-linearity caused by dipolar interactions betwe... more Abstract: We demonstrate a cooperative optical non-linearity caused by dipolar interactions between Rydberg atoms in an ultra-cold atomic ensemble. By coupling a probe transition to the Rydberg state we map the strong dipole-dipole interactions between Rydberg pairs onto the optical field. We characterize the non-linearity as a function of electric field and density, and demonstrate the enhancement of the optical non-linearity due to cooperativity.
Abstract We present a viewport for use in ultrahigh vacuum (UHV) based upon the preflattened sold... more Abstract We present a viewport for use in ultrahigh vacuum (UHV) based upon the preflattened solder seal design presented in earlier work [Cox etal, Rev. Sci. Instrum. 74, 3185 (2003)]. The design features significant modifications to improve long term performance. The windows have been leak tested to less than 10-10 atm cm 3/s.
Abstract. We report on a method of light-shift engineering where an auxiliary laser is used to tu... more Abstract. We report on a method of light-shift engineering where an auxiliary laser is used to tune the atomic transition frequency. We show that the technique provides enhanced loading of laser cooled 85 Rb and 87 Rb atoms into deep optical traps. Furthermore, by using a blue-detuned optical molasses, light-shift engineering offers remarkable spatial selectivity in the loading of an optical lattice.
Abstract We study the effect of a control beam on a electromagnetically induced transparency (EIT... more Abstract We study the effect of a control beam on a electromagnetically induced transparency (EIT) system in 87Rb. The control beam couples one ground state to another excited state forming a four-level N-system. Phase coherent laser beams to drive the N-system are produced using a double injection locking scheme. We show that the control beam can be used to Stark shift or split the EIT resonance.
As photons are the most robust carriers of quantum information, there is considerable interest in... more As photons are the most robust carriers of quantum information, there is considerable interest in developing singlephoton sources, memories, and gates. The storage and retrieval of single photons using electromagnetically induced transparency EIT 1 have been demonstrated experimentally in both laser-cooled 2 and thermal atomic ensembles 3. These experiments employ the dark-state polariton concept, where the photon is evolved into a single atomic spin excitation and back into a photon 4.
The electro-optic effect, where the refractive index of a medium is modified by an electric field... more The electro-optic effect, where the refractive index of a medium is modified by an electric field, is of central importance in nonlinear optics, laser technology, quantum optics and optical communications. In general, electro-optic coefficients are very weak and a medium with a giant electro-optic coefficient could have profound implications for precision electrometry and nonlinear optics at the single-photon level. Here we propose and demonstrate a giant d.c. electro-optic effect on the basis of polarizable (Rydberg) dark states. When a medium is prepared in a dark state consisting of a superposition of ground and Rydberg energy levels, it becomes transparent and acquires a refractive index that is dependent on the energy of the highly polarizable Rydberg state. We demonstrate phase modulation of the light field in the Rydberg-dark-state medium and measure an electro-optic coefficient that is more than six orders of magnitude larger than in usual Kerr media.
We report on a method of light-shift engineering where an auxiliary laser is used to tune the ato... more We report on a method of light-shift engineering where an auxiliary laser is used to tune the atomic transition frequency. The technique is used to selectively load a specific region of an optical lattice. The results are explained by calculating the differential light-shift of each hyperfine state. We conclude that the remarkable spatial selectivity of light-shift engineering using an auxiliary laser provides a powerful technique to prepare ultra-cold trapped atoms for experiments on quantum gases and quantum information processing.
By coupling a probe transition to a Rydberg state using electro-magnetically induced transparency... more By coupling a probe transition to a Rydberg state using electro-magnetically 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.
Journal of Physics B-atomic Molecular and Optical Physics, 2011
We study electromagnetically induced transparency (EIT) in the 5s$\rightarrow$5p$\rightarrow$46s ... more We study electromagnetically induced transparency (EIT) in the 5s$\rightarrow$5p$\rightarrow$46s ladder system of a cold $^{87}$Rb gas. We show that the resonant microwave coupling between the 46s and 45p states leads to an Autler-Townes splitting of the EIT resonance. This splitting can be employed to vary the group index by $\pm 10^5$ allowing independent control of the propagation of dark state polaritons. We also demonstrate that microwave dressing leads to enhanced interaction effects. In particular, we present evidence for a $1/R^3$ energy shift between Rydberg states resonantly coupled by the microwave field and the ensuing breakdown of the pair-wise interaction approximation.
We demonstrate a cooperative optical non-linearity caused by dipolar interactions between Rydberg... more We demonstrate a cooperative optical non-linearity caused by dipolar interactions between Rydberg atoms in an ultra-cold atomic ensemble. By coupling a probe transition to the Rydberg state we map the strong dipole-dipole interactions between Rydberg pairs onto the optical field. We characterize the non-linearity as a function of electric field and density, and demonstrate the enhancement of the optical non-linearity due to cooperativity.
Journal of Physics B-atomic Molecular and Optical Physics, 2008
We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas.... more We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas. We show that the onset of interactions is manifest as a depopulation of the Rydberg state and numerically model this effect by adding a density-dependent non-linear term to the optical Bloch equations. In the limit of a weak probe where the depopulation effect is negligible, we observe no evidence of interaction induced decoherence and obtain a narrow Rydberg dark resonance with a linewidth of <600 kHz, limited by the Rabi frequency of the coupling beam
We present a viewport for use in Ultra-high vacuum (UHV) based upon the preflattened solder seal ... more We present a viewport for use in Ultra-high vacuum (UHV) based upon the preflattened solder seal design presented in earlier work, Cox et al. Rev. Sci. Inst. 74, 3185 (2003). The design features significant modifications to improve long term performance. The windows have been leak tested to less than 10^-10 atm cm^3/s . From atom number measurements in an optical dipole trap loaded from a vapor cell magneto-optical trap (MOT) inside a vacuum chamber accommodating these viewports, we measure a trap lifetime of 9.5s suggesting a pressure of around 10^-10 Torr limited by background Rubidium vapor pressure. We also present a simplified design where the UHV seal is made directly to a vacuum pipe
Journal of Physics B-atomic Molecular and Optical Physics, 2009
We study the effect of a control beam on a Lambda electromagnetically induced transparency (EIT) ... more We study the effect of a control beam on a Lambda electromagnetically induced transparency (EIT) system in 87Rb. The control beam couples one ground state to another excited state forming a four level N-system. Phase coherent beams to drive the N-system are produced using a double injection scheme. We show that the control beam can be used to Stark shift or split the EIT resonance. Finally, we show that the when the control beam is on-resonance one observes a Doppler-free and sub-natural absorptive resonance with a width of order 100 kHz. Crucially, this narrow absorptive resonance only occurs when atoms with a range of velocities are present, as is the case in a room temperature vapour.
We present a design for a switchable nanomagnetic atom mirror formed by an array of 180° domain w... more We present a design for a switchable nanomagnetic atom mirror formed by an array of 180° domain walls confined within Ni80Fe20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror. We then describe the fabrication of a nanowire array and characterize its magnetic behavior using magneto-optic Kerr effect magnetometry, scanning Hall probe microscopy, and micromagnetic simulations, demonstrating how the mobility of the domain walls allow the atom mirror to be switched ``on'' and ``off'' in a manner which would be impossible for conventional designs. Finally, we model the reflection of 87Rb atoms from the atom mirror's surface, showing that our design is well suited for investigating interactions between domain walls and cold atoms.
We present a design for a switchable nanomagnetic atom mirror formed by an array of 180{\deg} dom... more We present a design for a switchable nanomagnetic atom mirror formed by an array of 180{\deg} domain walls confined within Ni80Fe20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror. We then describe the fabrication of a nanowire array and characterize its magnetic behavior using magneto-optic Kerr effect magnetometry, scanning Hall probe microscopy and micromagnetic simulations, demonstrating how the mobility of the domain walls allow the atom mirror to be switched "on" and "off" in a manner which would be impossible for conventional designs. Finally, we model the reflection of 87Rb atoms from the atom mirror's surface, showing that our design is well suited for investigating interactions between domain walls and cold atoms.
By coupling a probe transition to a Rydberg state using electromagnetically induced transparency ... more 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 nonlinearity as a function of probe strength and density. We demonstrate good quantitative agreement between the experiment and an N-atom cooperative model for N ¼ 3 atoms per blockade sphere and the n ¼ 60 Rydberg state.
Abstract We present a design for a switchable nanomagnetic atom mirror formed by an array of 180 ... more Abstract We present a design for a switchable nanomagnetic atom mirror formed by an array of 180 domain walls confined within Ni 80 Fe 20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror.
Abstract We study electromagnetically induced transparency (EIT) in the 5s→ 5p→ 46s ladder system... more Abstract We study electromagnetically induced transparency (EIT) in the 5s→ 5p→ 46s ladder system of a cold 87Rb gas. We show that the resonant microwave coupling between the 46s and 45p states leads to an Autler–Townes splitting of the EIT resonance. This splitting can be employed to vary the group index by±105 allowing independent control of the propagation of dark state polaritons. We also demonstrate that microwave dressing leads to enhanced interaction effects.
Abstract. We study electromagnetically induced transparency (EIT) of a weakly interacting cold Ry... more Abstract. We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas. We show that for Rydberg states with principal quantum numbers in the range n= 19���26, the onset of interactions is manifest as a depopulation of the Rydberg state. In the limit of a weak probe where the depopulation effect is negligible, we observe no evidence of interaction-induced decoherence and obtain a narrow Rydberg dark resonance with a linewidth of< 600 kHz.
Abstract We use the technique of electromagnetically induced transparency (EIT) to probe the effe... more Abstract We use the technique of electromagnetically induced transparency (EIT) to probe the effect of attractive dipole–dipole interactions in a highly excited Rydberg gas. The transient character of the EIT response is investigated by rapidly scanning the probe laser through resonance. We characterize the resulting cooperative optical non-linearity as a function of probe strength, density and scan direction. For the 58D5/2 Rydberg state, an atom density of 1.
Abstract: We demonstrate a cooperative optical non-linearity caused by dipolar interactions betwe... more Abstract: We demonstrate a cooperative optical non-linearity caused by dipolar interactions between Rydberg atoms in an ultra-cold atomic ensemble. By coupling a probe transition to the Rydberg state we map the strong dipole-dipole interactions between Rydberg pairs onto the optical field. We characterize the non-linearity as a function of electric field and density, and demonstrate the enhancement of the optical non-linearity due to cooperativity.
Abstract We present a viewport for use in ultrahigh vacuum (UHV) based upon the preflattened sold... more Abstract We present a viewport for use in ultrahigh vacuum (UHV) based upon the preflattened solder seal design presented in earlier work [Cox etal, Rev. Sci. Instrum. 74, 3185 (2003)]. The design features significant modifications to improve long term performance. The windows have been leak tested to less than 10-10 atm cm 3/s.
Abstract. We report on a method of light-shift engineering where an auxiliary laser is used to tu... more Abstract. We report on a method of light-shift engineering where an auxiliary laser is used to tune the atomic transition frequency. We show that the technique provides enhanced loading of laser cooled 85 Rb and 87 Rb atoms into deep optical traps. Furthermore, by using a blue-detuned optical molasses, light-shift engineering offers remarkable spatial selectivity in the loading of an optical lattice.
Abstract We study the effect of a control beam on a electromagnetically induced transparency (EIT... more Abstract We study the effect of a control beam on a electromagnetically induced transparency (EIT) system in 87Rb. The control beam couples one ground state to another excited state forming a four-level N-system. Phase coherent laser beams to drive the N-system are produced using a double injection locking scheme. We show that the control beam can be used to Stark shift or split the EIT resonance.
As photons are the most robust carriers of quantum information, there is considerable interest in... more As photons are the most robust carriers of quantum information, there is considerable interest in developing singlephoton sources, memories, and gates. The storage and retrieval of single photons using electromagnetically induced transparency EIT 1 have been demonstrated experimentally in both laser-cooled 2 and thermal atomic ensembles 3. These experiments employ the dark-state polariton concept, where the photon is evolved into a single atomic spin excitation and back into a photon 4.
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