1. The feasibility of Microwave- to-Optical Photon Efficient Conversion By Omar Alshehri Waterloo, ON Fall 2014 oalshehri@ksu.edu.sa

2. Outlines The device mechanism. Applications (potential). Advantages. Limitations. Improvements. The grand device!

3. Advantages of both Regimes separately MW photon Optical photon Linking quantum processors through low- loss optical fiber. Long-lived quantum- compatible storage [3,4]. Low-loss transmission [2]. Can be easily distributed [1]. Can be easily manipulated [1]

4. Advantages of converting Strengthens optical fiber transmission. Enables quantum systems to grow in bigger, more complex networks [5,6]. Linking quantum processors through low-loss optical fiber. MW easily manipulate d photon Optical easily distributed photon

5. Limitations The efficiency might be greater that unity which means that noise was added to the signal [1].

6. Previous potential conversion technology The only know potential device is the electro-optics modulators which is expected to act as converters [7-9]. However, some models have predicted photon number efficiencies of only few 10 -4 [10,11,8].

7. Mechanisms of potential devices The photon must enter a nonlinear medium before it can be converted [itself]. Proposed nonlinear intermediate mediums: 1- Clouds of ultracold atoms [12,13]. 2- Ensembles of spins [14,15]. 3- Nanomechanical resonators [16-18].

8. Current technology: nanomechanical resonator Both MW and optical lights have been used for cooling mechanical resonators to its ground state of motion [19,20]. Utilizing this common ground will enable combining optomechanics (optical photon related) and electromechanics (MW photon related). This combination is by simultaneously a mech. Resonator to both MW circuit and optical cavity [1]. The resonator components are as follows:

9. Detector MW circuit Optical photon Nano resonator Current technology: nanomechanical resonator (cont.) The device is composed of one mechanical resonator and two electromagnetic resonators: one optical and one MW. The optical resonator = Fabry-Perot cavity @ 282 THz. The MW resonator = LC circuit @ 7 GHz. The mechanical resonator system: LC circuit substrate + niobium coated membrane + the gap sandwiched between both of them.

10. Ref [1] 0- Maintain the cryogenics. 1- Inject a MW or optical field. 2- Measure the transmitted signals (seems random).

11. Current technology: nanomechanical resonator The best device fabricated today by Andrews et al [1] has conversion efficiency of 10%. This is the challenging part: integrating optical light with cryogenic temperatures. The cryogenics is needed for having 1- low noise, and 2- superconductivity. The ideal device should be 1- Coherent, 2- Lossless, and 3- Noiseless.

12. Future Improvements No technology nowadays can convert MW signal (low frequency) to optical (high frequency) while preserving the MW signal’s fragile quantum state [1]. The 10% efficiency device can improve in efficiency as proposed by [1] by precooling the device further lower than 4 K  below 40 mK. This is the challenging part: integrating optical light with cryogenic temperatures. The cryogenics is needed for having 1- low noise, and 2- superconductivity. The ideal device should be 1- Coherent, 2- Lossless, and 3- Noiseless.

13. References 1.Andrews, R. W., Peterson, R. W., Purdy, T. P., Cicak, K., Simmonds, R. W., Regal, C. A., & Lehnert, K. W. Bidirectional and ecient conversion between microwave and optical light. Nature Phys. 2911, 321–326 (2014). 2.O’Brien, J. L., Furusawa, A. & Vuckovic, J. Photonic quantum technologies. Nature Photon. 3, 687–695 (2009). 3.Buluta, I., Ashhab, S. & Nori, F. Natural and artificial atoms for quantum computation. Rep. Prog. Phys. 74, 104401 (2011). 4.Langer, C. et al. Long-lived qubit memory using atomic ions. Phys. Rev. Lett. 95, 060502 (2005). 5.Kimble, H. J. The quantum internet. Nature 453, 1023–1030 (2008). 6.Ladd, T. D. et al. Quantum computers. Nature 464, 45–53 (2010). 7.Cohen, D. A., Hossein-Zadeh, M. & Levi, A. F. J. Microphotonic modulator for microwave receiver. Electron. Lett. 37, 300–301 (2001). 8. Ilchenko, V. S., Savchenkov, A. A., Matsko, A. B. & Maleki, L. Whispering-gallery-mode electro-optic modulator and photonic microwave receiver. J. Opt. Soc. Am. B 20, 333–342 (2003). 9.Savchenkov, A. A. et al. Tunable optical single-sideband modulator withcomplete sideband suppression. Opt. Lett. 34, 1300–1302 (2009). 10.Tsang, M. Cavity quantum electro-optics. Phys. Rev. A 81, 063837 (2010). 11.Tsang, M. Cavity quantum electro-optics. II. input–output relations between traveling optical and microwave fields. Phys. Rev. A 84, 043845 (2011). 12.Hafezi, M. et al. Atomic interface between microwave and optical photons. Phys. Rev. A 85, 020302 (2012). 13.Verdú, J. et al. Strong magnetic coupling of an ultracold gas to a superconducting waveguide cavity. Phys. Rev. Lett. 103, 043603 (2009). 14. Imamoğlu, A. Cavity QED based on collective magnetic dipole coupling: Spin ensembles as hybrid two-level systems. Phys. Rev. Lett. 102, 083602 (2009). 15.Marcos, D. et al. Coupling nitrogen-vacancy centers in diamond to superconducting flux qubits. Phys. Rev. Lett. 105, 210501 (2010). 16.Safavi-Naeini, A. H. & Painter, O. Proposal for an optomechanical traveling wave phonon-photon translator. New J. Phys. 13, 013017 (2011). 17.Regal, C. A. & Lehnert, K. W. From cavity electromechanics to cavity optomechanics. J. Phys.: Conf. Ser. 264, 012025 (2011). 18.Bochmann, J., Vainsencher, A., Awschalom, D. D. & Cleland, A. N. Nanomechanical coupling between microwave and optical photons. Nature Phys. 9, 712–716 (2013). 19.Teufel, J. D. et al. Sideband cooling of micromechanical motion to the quantum ground state. Nature 475, 359–363 (2011). 20.Chan, J. et al. Laser cooling of a nanomechanical oscillator into its quantum ground state. Nature 478, 89–92 (2011).