Researchers from the University of Technology Sydney and TMOS, an Australian Research Council Centre of Excellence, have taken the fight to online hackers with a giant leap towards realizing affordable, accessible quantum communications, a technology that would effectively prevent the decryption of online activity. Everything from private social media messaging to banking could become more secure due to new technology created with a humble piece of scotch tape.

Quantum communication is still in its early development and is currently only feasible in very limited fields due to the costs associated with fabricating the required devices. The TMOS researches have developed new technology that integrates quantum sources and waveguides on chip in a manner that is both affordable and scalable, paving the way for future everyday use.

The development of fully functional quantum communication technologies has previously been hampered by the lack of reliable quantum light sources that can encode and transmit the information.

In a paper published today in ACS Photonics, the team describes a new platform to generate these quantum emitters based on hexagonal boron nitride – also known as white graphene. Where current quantum emitters are created using complex methods in expensive clean rooms, these new quantum emitters can be created using $20 worth white graphene pressed on to a piece of scotch tape.

These 2D materials can be pressed onto a sticky surface such as the scotch tape and exfoliated, which is essentially peeling to top layer off to create a flex. Multiple layers of this flex can then be assembled in a Lego-like style, offering a new bottom up approach as a substitute for 3D systems.

TMOS Chief Investigator Igor Aharonovich says “2D materials, like hexagonal boron nitride, are emerging materials for integrated quantum photonics, and are poised to impact the way we design and engineer future optical components for secured communication.”

In addition to this evolution in photon sources, the team have developed a high efficiency on-chip waveguide, a vital component for on-chip optical processing. Lead author, Chi Li  says “Low signal levels have been a significant barrier preventing quantum communications from evolving into practical, workable models. We hope that with this new development, quantum comms will become an everyday technology that improves people’s lives in new and exciting ways.”

Integration of hBN Quantum Emitters in Monolithically Fabricated Waveguides

Chi Li, Johannes E. Fröch, Milad Nonahal, Thinh N. Tran, Milos Toth, Sejeong Kim, and Igor Aharonovich

ACS Photonics, 20th August 2021

Hexagonal boron nitride (hBN) is gaining interest for potential applications in integrated quantum nanophotonics. Yet, to establish hBN as an integrated photonic platform several cornerstones must be established, including the integration and coupling of quantum emitters to photonic waveguides. Supported by simulations, we study the approach of monolithic integration, which is expected to have coupling efficiencies that are ∼4 times higher than those of a conventional hybrid stacking strategy. We then demonstrate the fabrication of such devices from hBN and showcase the successful integration of hBN single photon emitters with a monolithic waveguide. We demonstrate the coupling of single photons from the quantum emitters to the waveguide modes and collection from on-chip grating couplers. Our results build a general framework for monolithically integrated hBN single photon emitter and will facilitate future works toward on-chip integrated quantum photonics with hBN.