Quantum Optical Wavelength Converter

Abstract

An optical quantum state converter comprises an optical fiber input port configured to receive an optical signal comprising an optical quantum state at a first wavelength from an optical source. An optical combiner having a first input is coupled to the optical fiber input port. An optical pump source having an output that is coupled to a second input of the optical combiner provides an optical pump signal at a pump signal wavelength to a second input of the combiner. A nonlinear optical waveguide having an input that is coupled to an output of the optical combiner converts the optical quantum state at the first wavelength to an optical quantum state at a second wavelength determined by the optical pump signal.

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         27 . A method for converting a wavelength of an optical signal comprising an optical quantum state, the method comprising:
 a) receiving an optical signal comprising an optical quantum state with a first wavelength;   b) selecting an amplitude and phase as a function of frequency of an optical pump signal spectrum at a pump signal wavelength to form an optical pump signal that will convert a spectra of the optical signal comprising the optical quantum state to a desired spectra;   c) combining the received optical signal comprising the optical quantum state with the first wavelength and the selected optical pump signal, thereby forming a combined optical signal;   d) propagating the combined optical signal through a nonlinear optical waveguide that converts the optical quantum state with the first wavelength to an optical quantum state at a second wavelength; and   e) filtering the combined optical signal to suppress at least some of the optical pump signal to a desired residual pump level and to preserve a quantum property of the converted optical quantum state at the second wavelength.   
     
     
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         34 . The method of  claim 27  wherein the first wavelength is a wavelength in a range of 760 nm to 800 nm and the amplitude and phase as a function of frequency of the optical pump signal spectrum is selected so that the second wavelength is a wavelength in a range of 1445 nm to 1605 nm. 
     
     
         35 . The method of  claim 27  wherein the first wavelength is a wavelength in a range of 1445 nm to 1605 nm and the amplitude and phase as a function of frequency of the optical pump signal spectrum is selected so that the second wavelength is a wavelength in a range of 760 nm to 800 nm. 
     
     
         36 . The method of  claim 27  wherein the selecting the amplitude and phase as a function of frequency of the optical pump signal spectrum that will convert a spectra of the optical signal comprising the optical quantum state to a desired spectra comprises selecting an optical pump signal spectrum with a tunable optical pump source. 
     
     
         37 . The method of  claim 27  wherein the selecting the optical pump signal spectrum that will convert a spectra of the optical signal comprising the optical quantum state to a desired spectra further comprises linearly chirping the pump signal spectrum. 
     
     
         38 . The method of  claim 27  wherein the nonlinear optical waveguide narrows the optical spectrum of the converted optical quantum state with the second wavelength. 
     
     
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         42 . The method of  claim 27  wherein the propagating the combined optical signal through the nonlinear optical waveguide comprises propagating the combined optical signal through a tunable nonlinear optical waveguide. 
     
     
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         47 . The method of  claim 27  wherein the filtering suppresses at least some of the optical pump signal to a level that is greater than 90 dB. 
     
     
         48 . An optical quantum state converter comprising:
 a) an optical pump source comprising a dispersive element and a spatial light modulator that provides an optical pump signal having an amplitude and phase as a function of frequency at a pump optical signal wavelength to an output;   b) an optical combiner having a first input configured to receive an optical signal comprising an optical quantum state at a first wavelength and a second input coupled to the output of the optical pump source;   c) a nonlinear optical waveguide having an input that is coupled to an output of the optical combiner, the nonlinear optical waveguide converting the optical quantum state at the first wavelength to an optical quantum state at a second wavelength, wherein the amplitude and phase as the function of frequency of the optical pump signal is chosen to convert a spectra of the optical signal comprising the optical quantum state to a desired spectra; and   d) a filter having an input coupled to the output of the nonlinear optical waveguide, the filter suppressing at least some of the optical pump signal to a desired residual pump level and preserving a quantum property of the converted optical quantum state at the second wavelength.   
     
     
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         50 . The optical quantum state converter of  claim 48  wherein the optical source comprises a single-photon optical source, a quantum memory, an optical logic gate, or an optical fiber transport system. 
     
     
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         59 . The optical quantum state converter of  claim 48  wherein the optical pump source is configured to generate an optical spectrum having a linearly chirped spectrum. 
     
     
         60 . The optical quantum state converter of  claim 48  wherein the desired spectra of the optical quantum state at the second wavelength has a linewidth that is in a range of 1-1000 kHz 
     
     
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         68 . The optical quantum state converter of  claim 48  wherein the optical filter is configured to suppress the tunable optical pump signal to a level that is greater than 90 dB. 
     
     
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         80 . A method for converting a wavelength of an optical signal comprising an optical quantum state, the method comprising:
 a) receiving an optical signal comprising an optical quantum state with a first wavelength;   b) selecting an amplitude and phase as a function of frequency of an optical pump signal spectrum at a pump signal wavelength to form an optical pump signal having a chirp magnitude and sign that will convert a spectra of the optical signal comprising the optical quantum state to a spectra having a desired bandwidth;   c) combining the received optical signal comprising the optical quantum state with the first wavelength and the selected optical pump signal, thereby forming a combined optical signal;   d) propagating the combined optical signal through a nonlinear optical waveguide that converts the optical quantum state with the first wavelength to an optical quantum state at a second wavelength; and   e) filtering the combined optical signal to suppress at least some of the optical pump signal to a desired residual pump level and to preserve a quantum property of the converted optical quantum state at the second wavelength.   
     
     
         81 . The method of  claim 80  wherein the converted spectra has the desired bandwidth and a desired phase. 
     
     
         82 . The method of  claim 80  wherein the nonlinear optical waveguide narrows the optical spectrum of the converted optical quantum state with the second wavelength. 
     
     
         83 . The method of  claim 80  wherein the propagating the combined optical signal through the nonlinear optical waveguide comprises propagating the combined optical signal through a tunable nonlinear optical waveguide. 
     
     
         84 . The optical quantum state converter of  48  wherein the nonlinear optical waveguide comprises a periodically poled waveguide. 
     
     
         85 . The method of  claim 42  wherein the preserving the quantum property of the converted optical quantum state at the second wavelength comprises preserving at least one of entanglement, phase coherence, or photon statistics. 
     
     
         86 . The optical quantum state converter of  48  wherein the optical pump source provides a continuous wave optical pump signal.