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Experiment

Results. Motivation. Experiment. Below: experimental setup used for light storage experiments. Below: Gray line indicates the transmission in Pr+SiO 5 when the coupling beam is off. Dark line is with coupling beam on.

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Experiment

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  1. Results Motivation Experiment Below: experimental setup used for light storage experiments Below: Gray line indicates the transmission in Pr+SiO5 when the coupling beam is off. Dark line is with coupling beam on • Advances in quantum computers means there is a need for devices which can act as quantum memories. • Slowing down and stopping light pulses in a medium provides a way of mapping all the information from the pulse into the medium in the form of a spin wave. Stopped Light With Storage Times Greater than 1 second using Electromagnetically Induced Transparency in a SolidJ.J Londell, E. Fravel, M.J. Sellars and N.B. Manson, Phys. Rev. Lett. 95 063601 (2005) Transmission Through Pr+SiO5 • transmission peak is exhibited at the resonance frequency (EIT was demonstrated) • Narrow transparency window Dynamic EIT EIT (electromagnetically induced transmission makes use of the Dark State of a system. In this state, the simultaneous presence of the control and signal beam couple with the system atomic states to forbid some excitations (thus absorptions of photons) of the atomic states. The beams are then transmitted. As a toy model, it is helpful to think of: x^2 - x^4 + x^6 • light stored in Pr+ SiO5 crystal - material chosen because 5/2 spin of Pr+ nuclei provide ground states for EIT via Zeeman splitting in a B field • counterpropogating beams for distinguishing probe and coupling beams easily Storage Time • efficiency decreases exponentially as the storage time increases • due to decoherence of spin wave from scattering process Left: energy levels of Pr+SiO5 in B field • fine splitting due to B field • repump pulses prepare the correct conditions for EIT • probe beam and coupling beam form transparent state The rapid change of refractive index within the transparency window (∆ω) slows down the beams as: Below: sequence of laser pulses applied towith Pr+SiO5 Above: (a) 2 rephasing pulses used (b) many rephasing pulses used ∆ω and [dn(ω)/dω]-1 are proportional to the control beam intensity. When the control beam is switched off, ∆ω and vggo to 0 and there is no photon transmitted. However, the Dark State (excitations of Polaritons) is maintained and the signal beam information is mapped to the spin coherence of system atomic states. When the control beam is switched on again, the process reverses and the signal beam is retrieved. Future work • Decoherence due to the environment • Optimization of photon storage • Generalization to photonic crystal • Application to quantum memory • coupling beam turned off after probe applied • RF pulses applied with two techniques: 1. with 2 pulses (top) 2. with many pulses (bottom)

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