Techniques for bidirectional transduction of quantum level signals between optical and microwave frequencies using a common acoustic intermediary
Embodiments described herein include systems and techniques for converting (i.e., transducing) a quantum-level (e.g., single photon) signal between the three wave forms (i.e., optical, acoustic, and microwave). A suspended crystalline structure is used at the nanometer scale to accomplish the desired behavior of the system as described in detail herein. Transducers that use a common acoustic intermediary transform optical signals to acoustic signals and vice versa as well as microwave signals to acoustic signals and vice versa. Other embodiments described herein include systems and techniques for storing a qubit in phonon memory having an extended coherence time. A suspended crystalline structure with specific geometric design is used at the nanometer scale to accomplish the desired behavior of the system.
1. A system for transducing a quantum signal, comprising:
an optical device;
a suspended crystalline optical waveguide configured to propagate a quantum optical signal, the suspended crystalline optical waveguide being optically coupled to the optical device;
a first suspended crystalline transducer coupled to the suspended crystalline optical waveguide, the first suspended crystalline transducer comprising a plurality of holes that are configured to trap and convert a quantum signal between the quantum optical signal and a quantum acoustic signal, wherein the first suspended crystalline transducer oscillates at a tuning frequency during transduction;
a second suspended crystalline transducer coupled to the first suspended crystalline transducer, the second suspended crystalline transducer configured to oscillate at the tuning frequency to convert the quantum signal between the quantum acoustic signal and a single-photon level microwave signal; and
a conductor coupled to the second suspended crystalline transducer wherein the suspended crystalline optical waveguide is surrounded by a plurality of suspended crystalline structures, disposed in a geometric design to isolate the quantum optical signal outside of the suspended crystalline optical waveguide.
2. The system for transducing the quantum signal of claim 1 , wherein the second suspended crystalline transducer comprises a piezoelectric material overlay of a suspended crystalline structure.
3. The system for transducing the quantum signal of claim 2 , wherein the piezoelectric material comprises Aluminum Nitride.
4. The system for transducing the quantum signal of claim 2 , further comprising:
a plurality of conductors that are electrically coupled to the piezoelectric material overlay of the suspended crystalline structure, wherein the plurality of conductors form an interleaved pattern and provide alternating polarity electrical signals to the piezoelectric material to generate an oscillation at the tuning frequency.
5. The system for transducing the quantum signal of claim 1 , wherein:
the second suspended crystalline transducer comprises a suspended crystalline structure and a plurality of conductors overlaying the suspended crystalline structure;
the plurality of conductors are configured to form a plurality of capacitive features;
during transduction, the plurality of capacitive features oscillate at the tuning frequency to generate a changing capacitance; and
the single-photon level microwave signal is generated based on the changing capacitance.
6. The system for transducing the quantum signal of claim 1 , wherein the suspended crystalline optical waveguide, the first suspended crystalline transducer, and the second suspended crystalline transducer each comprise silicon.
7. The system for transducing the quantum signal of claim 1 , wherein the suspended crystalline optical waveguide, the first suspended crystalline transducer, and the second suspended crystalline transducer are disposed in a single crystal silicon layer of a silicon-on-insulator substrate.
8. The system for transducing the quantum signal of claim 1 , wherein the conductor comprises aluminum.