Design of an ultra-low mode volume piezo-optomechanical quantum transducer

Abstract

Coherent transduction of quantum states from the microwave to the optical domain can play a key role in quantum networking and distributed quantum computing. We present the design of a piezo-optomechanical device formed in a hybrid lithium niobate on silicon platform, that is suitable for microwave-to-optical quantum transduction. Our design is based on acoustic hybridization of an ultra-low mode volume piezoacoustic cavity with an optomechanical crystal cavity. The strong piezoelectric nature of lithium niobate allows us to mediate transduction via an acoustic mode which only minimally interacts with the lithium niobate, and is predominantly silicon-like, with very low electrical and acoustic loss. We estimate that this transducer can realize an intrinsic conversion efficiency of up to 35% with <0.5 added noise quanta when resonantly coupled to a superconducting transmon qubit and operated in pulsed mode at 10 kHz repetition rate. The performance improvement gained in such hybrid lithium niobate-silicon transducers make them suitable for heralded entanglement of qubits between superconducting quantum processors connected by optical fiber links.

Optomechanical Microwave-to-Optical Photon Transducer Chips: Empowering the Quantum Internet Revolution

“…One of the most successful experiments in this structure was conducted by Painter's group [29,30], which achieved the complete process from excitation of superconducting qubits to optical photon transmission. They employed a hybrid platform of AlN-on-Si, designing the dimensions of the piezoelectric cavity to match both the periodic mechanical modes and the periodicity of the IDTs, thereby significantly enhancing the electromechanical coupling rate.…”

“…The single-phonon initialization probability reached 75%. The experiment was carried out at low temperatures (15 mK) and under low power pumping (n cav,o = 44), successfully reducing the added noise to a sub-photon level ( N add ∼ 0.57) and achieving a total conversion efficiency of ∼ 10 −5 [29,30].…”

“…The key feature of optomechanical quantum transducers, as shown in Figure 2, is the utilization of mechanical resonators as intermediaries to complete the microwave-to-optical conversion via microwave-phonon and phonon-photon. Available mechanical resonators include membrane films [25][26][27][28], phononic crystals [29][30][31][32][33][34][35][36], microdisks [37,38], and bulk acoustic wave resonators [39,40], forming a diverse array of optomechanical transducer structures with different performances.…”

Remote cross-resonance gate between superconducting fixed-frequency qubits

“…Quantum chips separated by long distances in a refrigerator are connected through superconducting coaxial cables that pass microwave signals [5,6,[21][22][23][24][25][26][27][28][29], millimeter-wave photonic links [30], or acoustic transmission lines as quantum phononic channels [31,32]. For connecting qubits in different refrigerators or sending quantum information to the so-called quantum internet, quantum information stored in superconducting qubits must be frequency-converted into optical photons [7,[33][34][35][36][37][38][39][40]. However, it is very challenging to overcome large energy differences and achieve high conversion efficiencies.…”