On-chip Silicon Carbide Platform for Photonic Quantum Technologies

Abhishek Purohit

In terms of the precision of its predictions, quantum physics is the most successful scientific theory ever developed. Today, we are learning to harness quantum properties such as entanglement and coherence to realize profoundly new technologies. Among these, the devices implementing quantum information are arguably the most rapidly developing with the potential to establish a new paradigm in fields like computation, data processing and communication.

The most advanced demonstrations of quantum information have been implemented by superconductor qubits [1], trapped ions /atoms [2] and photons [3]. Optically active crystal defects, however, have emerged as an outstanding new platform as they lend themselves to on-chip large integration [4] and room temperature operation [5]. They have been proposed for the realization, for example, of long-distance quantum communication architectures [6], quantum repeaters [7, 8] and network-based quantum computation [9].

Silicon Carbide (SiC) hosts a wide variety of such defects [10] with the added advantage of being a CMOS-compatible semiconductor with wide-band gap and a growing utilization in industry (e.g.: power electronics). The latter, a circumstance that ensures availability on the market of high-quality wafer-scale substrates and well-established microfabrication processes.

At the core of many transformative proposals involving defects is a spin-photon interface to generate robust flying qubits where quantum information is encoded. A well-known issue is the efficient interaction between single defects and photons. Many recent breakthroughs, however, have been enabled by circumventing this issue via integration with nanophotonic functional devices [11, 12]. For example, by coupling a defect with a nanophotonic cavity, we can dramatically enhance the photon emission rate into a single cavity mode [13, 14, 15].

Figure 1: Key milestones in integrated quantum photonics in the past decade. [16]

Researchers are working to explore a SiC platform for photonic quantum technologies where classical nanophotonics structures (e.g., waveguides and nanocavities) are monolithically integrated on a chip to single defects to develop and study circuits, devices, systems, and solutions for scaling up SiC integrated photonics. The importance of this study would be enormous since it would pave the door for more scalable quantum computers. It could also be employed to achieve optical switching at the level of a few photons and ultra-fast single photon emission, with enormous implications on a variety of fields spanning quantum networks, sensing, and information processing.

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