Four Illinois researchers present at international quantum information conference

9/1/2023 9:52:37 AM Sarah Maria Hagen

After hosting last year's conference, the University of Illinois was represented at this year's Theory of Quantum Computation, Communication, and Cryptography (TQC) conference in Aveiro, Portugal by four IQUIST members.

Felix Leditzky, assistant professor in the Department of Mathematics presented a talk about the duality between quantum superdense coding – sending more classical bits with fewer entangled quantum bits – and quantum teleportation, which "teleports" an arbitrary quantum state using entangled qubits and classical communication.

The relationship between the two protocols is well known in quantum information science, but by viewing each task as a state discrimination problem Leditzky and collaborator Eric Chitambar (ECE) were able to derive new results about the ability to perform both protocols in the noisy setting. "Your ability to teleport an unknown state is related to your ability to discriminate a certain set of states – this is exactly the dense coding protocol [one tries] to solve. This observation gave us a tool to quantify this duality in noisy cases, which was not known previously", Leditzky explains.

One major result of the work was that bound entangled states cannot beat a classical success rate on teleportation: "The state discrimination picture can be used to determine a necessary and sufficient criterion for the [entangled] states that can be used to break the classical limit, and we can do that for both [teleportation and superdense coding] because of the duality". For those interested, this and other talks by Dr. Leditzky can be found on his website.

Illinois faculty member Felix Leditzky addresses the TQC audience remotely. (Image: Sarah Maria Hagen)

Post-doctoral researcher Stefano Chessa and graduate students Louis Schatzki and Sarah Hagen exhibited their respective research at the conference's Tuesday poster session. For Chessa, his three posters represented contributions connected to quantum Shannon theory, error detection, and quantum thermodynamics as a graduate student researcher at Scuola Normale Superiore in Pisa, Italy and at Los Alamos National Laboratory. Schatzki presented on a connection between concentratable and multipartite entanglement with coding theory, as well as work building symmetry explicitly into quantum machine learning models, while Hagen's poster concerned a non-classical version of a previously introduced cryptographic reduction and its connection to constructing cryptographic primitives. More information about the work presented can be found on the conference's website.

Insert caption here — Dr. Stefano Chessa, a post-doctoral researcher at Illinois, presents his research. (Image: Sarah Maria Hagen)

Next to the variety of talks by researchers concerning quantum computation, communication, and cryptography, the conference also provided an opportunity for the attendees to socialize. Next to the conference dinner, hosted at the Aveiro marina, they were able to choose between a visit to the local science museum, a walk through the salt ponds, and a Moliceiro boat tour along the city's canals.

The conference's events included a tour of the Marinha da Noeirinha salt farms where salt is produced locally by passing salt water through a series of pools of increasing salinity before salt can be harvested.&amp;nbsp;(Image: Sarah Maria Hagen) — The conference's events included a tour of the Marinha da Noeirinha salt farms where salt is produced locally by passing salt water through a series of pools of increasing salinity before salt can be harvested. (Image: Sarah Maria Hagen)

Illinois' presence at TQC was fitting in light of the university's role as TQC host location at last year's meeting, the first in-person iteration of the conference post-pandemic, for which Drs. Leditzky and Chitambar served as part of the local organizing committee. As had been the case pre-pandemic, TQC is set to change between international locations on an annual basis. Next year, the conference will take place at the Okinawa Institute of Science and Technology (OIST) in Okinawa, Japan.