Sources, Memories, Detectors Ryan Camacho, Curtis Broadbent, Michael Pack, Praveen Vudya Setu, Greg Armstrong, Benjamin Dixon and John Howell University of Rochester Collaboration with Bob Boyd $Thanks to$: DARPA, ARO, PECASE, NSF, Research Corporation, ARO MURI, DURIP, University of Rochester

Group

Overview Goals –Sources, Memories and Readout of Quantum Images Quantum Buffering Stopped Images (>1000 pulse delays) Entanglement Preservation Time-energy Biphoton Absorption Image Readout

Sources, Memories and Detection SourceMemoryDetection Source produces quantum images Memory stores image Images are Eigenstates of detection

Memories Use steep linear dispersion between two absorption resonances to slow down Quantum and Classical Images Preserve Images (not just binary signals) for large delays Ultra-low noise (preserve quantum fields in low loss regime) Doppler broadened vapors Have delayed 275 ps pulses in excess of 10 ns and 740 ps pulses in excess of 60 ns. Small broadening: Dispersive broadening dominates absorptive broadening. Cesium Resonances and Delays Camacho et al., Phys Rev Lett 98, (2007) Macke et al., Phys. Rev. A 73, (2006).Phys. Rev. A 73, (2006) H. Tanaka et al., Phys. Rev. A 68, (2003).Phys. Rev. A 68, (2003) Linear Circuits

Image Buffering Experiment Camacho et al, Phys. Rev. Lett. 98, (2007)

Classical Image Interference Matched image pulses (high fringe visibility) Unmatched image pulses (low Local oscillator pulse and slow light pulse arrive at same time at the beam splitter (interference) Arrive at different times

Weak Coherent State 2-D Imaging 3ns delay of 2-d image, 0.8 photons per pulse and (right) 2d image propagating through air, 0.8 photons per pulse.

Weak Coherent State 1-D Imaging 0.5 photons, on average, per pulse hit a 2 bar test pattern. The image pulses are delayed by 9 ns. A multimode fiber is used to scan the image.

Entanglement Preservation in Buffer 5s 1/2 5p 1/2 5p 3/2

Potential Digital signal processing Holography Remote imaging Quantum buffers Scenedow? Etc.

Stopped Light Vapor Cell with Buffer Gas

Slow Light Experiment

EIT: Feynman Diagrams |1  |3  |2 

Stopped Light Results Pump turned off Pump turned on

Stopped Light In Hot Vapors 1000 delays

Stopping Transverse Quantum Images Developing a transverse image storage device for quantum images Stack Multiple Images in the medium Readout any image in the stack at will: Images on demand

PBS  A1 A2 Alice Time Stamping Sync Generator RS PBS  B1B2 Bob Time Stamping PPS 50/50 BS 50/50 Fiber BS PPS – Passive Power Splitter RS – Raw Sync Energy-Time Quantum Cryptography Simplified View Type-I BBO 50mW Internet Computer B Computer A

Time-Time Correlations Multistate state cryptosystem. Time bin Alice and Bob both measure their Photon at the same point in the time bin 0123 Alice Bob 0,34,25,92,45 Large Bin Synch Pulses ever 64 ns

Sifted Key Bit Rates Qudit to Qubit conversion Example: 1024 alphabet qudit converted to 10 bits I. Ali Khan, C. Broadbent, J.C. Howell, PRL 98, (2007)

Franson Interferometer: Measure Energy Correlations Output ports of Michelson with postselection of short-short and long long Using temporal commutator relation, normal ordering and assuming l 1 ~ l 2 QND Measurement

Franson Visibility as a function of Eve’s measurement in time for Gaussian POVM Fringe Visibility Eve’s Temporal Uncertainty for QND 3 meters 10 meters

Biphoton Absorption  pump ~1 MHz  pdc ~10 THz signal idler 5s 1/2 5p 3/2 5D 5/2 Rb

Two Photon Absorption in Fiber Nanotapers and Holey Fibers Evanescent Field Coupling or Mode confinement Small mode volume Linear Biphoton Intensity response Switching Close to Completion

Conclusions Delayed transverse image in slow light medium– preserved amplitude and phase Low noise, linear device useful for quantum information preservation. Demonstrated multiple pulse delays with little pulse distortion. Slow Light FTI, Preservation of quantum signals, and 1000’s of pulse delays Many interesting possibilities –Gravitometry –Stopped Images

Recent Work