A new method for reducing “crosstalk” between laser beams used to operate ion trap quantum computers could help the Department of the Air Force (DAF) and its partners use quantum processors more effectively.
A team of researchers affiliated with the Air Force Research Laboratory (AFRL) Information Directorate (RI) recently secured a patent from the U.S. Patent and Trademark Office related to this crosstalk reduction capability. The team includes Dr. Michael Fanto, Dr. David Hucul, Dr. Matt Smith, Dr. Zachary Smith, Dr. Christopher Tison, and Dr. Kathy-Anne Soderberg, alongside Dr. Stefan Preble of the Rochester Institute of Technology.
Quantum computers use quantum mechanics principles to perform certain calculations faster than traditional computers can. Using the principle of superposition, qubits – the quantum computing equivalent of normal computer bits – can exist in any simultaneous combination of the states 0 and 1. Additionally, wave-like interference of the qubits can be harnessed to create entanglement, allowing quantum computers to process large amounts of information simultaneously.
Quantum computers have the potential to address a variety of complex problems, such as scheduling logistics operations within complicated global supply chains and prioritizing targets for attack in fast-moving, large-scale, real-time combat operations. Such problems are computationally impossible for classical computers to complete due to the problems’ sheer scale and complexity. Compact quantum systems can also be placed on drones to enable secure, encrypted communication networks in flight, or to provide enhanced sensing capabilities – such as Position, Navigation, and Timing (PNT) capabilities – without needing GPS.
Trapped ion quantum computers use arrays of charged atoms suspended in a vacuum by electromagnetic fields. Lasers then manipulate these trapped ions to act as quantum bits. Because the ions are separated by only a few millionths of a meter, controlling the atoms individually and precisely without any crosstalk from an adjacent laser beam is a significant engineering challenge, especially when large numbers of qubits are involved. Additionally, these control lasers rely on large-scale optical systems to deliver light to the trapped ions. These bulky systems are not readily scalable for controlling many qubits.
The team’s patented innovation involves using integrated photonic chips to act as circuit boards for light. These chips are made in the same foundries as standard computer chips, although integrated photonics chips are designed to channel and manipulate light rather than electricity. AFRL team members realized that they could fabricate novel features directly onto the chips to minimize the amount of laser light scattered. This fabrication process involves making small indentations in the chip to separate waveguides and adding light-absorbing materials.
With these new features, lasers can address individual ions with significantly reduced crosstalk occurring between neighboring ions. Additionally, because the integrated photonics chip replaces many traditional optical components, the size of a bulk optical assembly can be reduced from a few square meters to less than one square centimeter. The team's invention thus increases the manufacturing readiness of ion trap systems while significantly reducing their Size, Weight, and Power (SWaP) demands. This innovation will soon accelerate the use of quantum systems in the field and provide DAF with significant new opportunities in quantum information science. Dr. Matt Smith of the RI team noted that the innovation has already achieved a world record for minimizing crosstalk in ion trap addressing.
Implementing this innovation widely will not require new manufacturing capabilities. Integrated photonics chips modified to contain these patented attributes can be produced by existing computer chip foundries, many of which are owned by commercial entities. The AFRL team’s invention was one of the technologies featured in the Department of War’s recent patent holiday, which offered no-fee Commercial Evaluation Licenses (CELs) for a curated selection of innovations to commercial partners. This initiative was inaugurated to accelerate the commercialization of new technologies to ultimately provide the warfighter with enhanced capabilities, and the inclusion of the RI team’s innovation in the event is a testament to the potential benefits it brings to DAF’s objectives.
The RI team’s patent application was facilitated by RI’s Office of Research and Technology Application (ORTA). DAF ORTAs help DAF scientists and engineers navigate the patent application and issuance process to ensure preservation of intellectual property interests. After patent issuance, many technologies are licensed to external entities for further development, a process also facilitated by ORTAs. DAF ORTAs coordinate their activities with the DAF Technology Transfer and Transition (T3) Program Office, which oversees individual ORTAs and performs ORTA functions for DAF laboratories lacking a designated office.
United States Patent Office Patent #12,468,087
About AFRL
The Air Force Research Laboratory, or AFRL, is the primary scientific research and development center for the Department of the Air Force. AFRL plays an integral role in leading the discovery, development, and integration of affordable warfighting technologies for our air, space, and cyberspace forces. With a workforce spanning across nine technology areas and 40 other operations around the globe, AFRL provides a diverse portfolio of science and technology ranging from fundamental to advanced research and technology development. For more information, visit www.afresearchlab.com.