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Machine-assisted scalable fabrication of ultrafast quantum photonic devices

Strategic Research Initiatives

Simeon I. Bogdanov, Dept. of Electrical and Computer Engineering

Bryan K. Clark, Dept. of Physics

Prashant K. Jain, Dept. of Chemistry and Materials Research Lab

Quantum photonic networks (QNs) are essential to enable secure communication systems, multi-core quantum processors and quantum-assisted distributed sensing, promising a revolution in modern technology. QNs suffer from the sluggish rate at which the desired quantum states of light can be prepared and processed. For example, the rates of distant entanglement generation are often in the kHz range or below. This issue is rooted in the probabilistic nature of photon generation, transmission, and logical operations and highlights our insufficient control of light–matter interaction at the quantum level. A strong and targeted enhancement of light–matter interactions to THz-scale rates could propel communication and entanglement rates into the MHz or even GHz range, making quantum photonic networks and sensors practically viable. With these rates, one could tolerate high levels of quantum dephasing, inviting the use of many promising quantum systems and materials that would be otherwise disqualified due to short coherence times. Many of the typically GHz-scale inter-component frequency mismatches would be less detrimental to the scalability of the system. Finally, quantum photonic circuits based on quantum emitters may even be able to do away with cryogenic cooling.

QNs could operate at practically viable rates if ultrafast quantum photonic devices were widely available and co-integrated on the same material platform; but these devices remain challenging to fabricate, especially in a scalable manner. For most dielectric photonic resonant systems, the ability to achieve THz-scale photon rates from quantum emitters is restricted by the optical diffraction limit. Moreover, mature photonic platforms, such as Si or SiN-based circuits alone, despite spectacular advances, cannot host all the active devices required by QNs.

Our strategy to realize on-chip ultrafast quantum photonic devices is based on hybrid deterministic integration of quantum emitters, plasmonic nanostructures, and emerging photonic material platforms. Individual components will be produced by tailorable chemical synthesis and integrated on chip by a deterministic and high-throughput assembly process enabled by deep learning. The strongly enhanced interaction between on-chip photons and quantum dipole emitters by way of coupling to low-loss plasmonic nanostructures, will enable ultrafast quantum and classical photonic components with bitrates in the GHz range operating at cryo-free temperatures. Through such integration, we aim to achieve orders-of-magnitude enhanced light–matter interaction, up to THz-scale rates, and erasing the effects of quantum decoherence and dipole emitter inhomogeneity. Our interdisciplinary effort tackles the long-standing challenge of scalable fabrication of ultrafast cryo-free quantum photonic systems. To this end, in SRI phase I, we will advance science and engineering on three fronts:

  1. Chemical synthesis and large-scale optical screening of nanoparticle-based quantum emitters and low-loss crystalline plasmonic nanostructures.
  2. Advancing a scanning probe-based method and employing it to tightly integrate pre-selected quantum emitters and plasmonic resonators with on-chip photonic circuitry.
  3. Use of deep neural networks and reinforcement learning for dramatically speeding up nanoparticle characterization and pick-and-place procedures.

 

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Overview of the proposed project within the broader aspiration for ultrafast quantum photonic information networks. A scalable method for hybrid on-chip assembly of nanoscale building blocks will be developed for ultimately realizing quantum photonic devices that operate at GHz bitrates and under cryo-free conditions.