Mikio Kozuma

Learn More
We have observed Bragg diffraction of a Bose-Einstein condensate of sodium atoms by a moving, periodic, optical potential. The coherent process of Bragg diffraction produced a splitting of the condensate with unidirectional momentum transfer. Using the momentum selectivity of the Bragg process, we separated a condensate component with a momentum width(More)
Storage and retrieval of a squeezed vacuum was successfully demonstrated using electromagnetically induced transparency. The squeezed vacuum pulse having a temporal width of 930 ns was incident on the laser cooled 87Rb atoms with an intense control light in a coherent state. When the squeezed vacuum pulse was slowed and spatially compressed in the cold(More)
Propagation of a light pulse through a high-Q optical microcavity containing a few cold atoms (N<10) in its cavity mode is investigated experimentally. With less than ten cold rubidium atoms launched into an optical microcavity, up to 170 ns propagation lead time ("superluminal"), and 440 ns propagation delay time (subluminal) are observed. Comparison of(More)
We have succeeded in observing ultraslow propagation of squeezed vacuum pulses with electromagnetically induced transparency. Squeezed vacuum pulses (probe lights) were incident on a laser-cooled 87Rb gas together with an intense coherent light (control light). A homodyne method sensitive to the vacuum state was employed for detecting the probe pulse(More)
Storage and retrieval of parametric down-conversion (PDC) photons are demonstrated with electromagnetically induced transparency (EIT). Extreme frequency filtering is performed for THz order of broadband PDC light and the frequency bandwidth of the light is reduced to MHz order. Storage and retrieval procedures are carried out for the frequency filtered PDC(More)
We construct a Mach-Zehnder interferometer using Bose-Einstein condensed rubidium atoms and optical Bragg diffraction. In contrast to interferometers based on normal diffraction, where only a small percentage of the atoms contribute to the signal, our Bragg diffraction interferometer uses all the condensate atoms. The condensate coherence properties and(More)
The squeezed vacuum resonant on the (87)Rb D1 line (probe light) was injected into an optically dense rubidium gas cell with a coherent light (control light). The output probe light maintained its quadrature squeezing within the transparency window caused by the electromagnetically induced transparency (EIT). The results reported here are the first(More)
We show that by strongly modifying the dispersion properties of a four-level system, non-existing wave mixing channels can be opened and significantly enhanced. Specifically, we show that coherent optical four-wave mixing with a pump wave mediated by electromagnetically induced transparency (thereby propagating with an extremely slow group velocity) will(More)
Various atom-photon entangled states can be generated by utilizing corresponding conservation law. In particular, higher-dimensional entanglement between an atomic ensemble and a photon is expected to arise from angular momentum conservation law. Here we demonstrate entanglement of or-bital angular momentum states by utilizing atomic collective excitation(More)
Three-dimensional entanglement of orbital angular momentum states of an atomic qutrit and a single photon qutrit has been observed. Their full state was reconstructed using quantum state tomography. The fidelity to the maximally entangled state of Schmidt rank 3 exceeds the threshold 2/3. This result confirms that the density matrix cannot be decomposed(More)