Science Advances: Quantum Conference Key Agreement

Most of us have spent an inordinate amount of time over the past year in online conference calls, which are sure to become a regular feature in our lives. Recent events such as the ransomware attacks on US energy firms have highlighted more than ever the need for information security in such electronic forms of communication.

In a collaboration with the Mostly Quantum Lab at Heriot-Watt, we demonstrated the first quantum-secure conference call between four users. Using a multi-photon entangled GHZ state distributed over fiber-optic cables with a combined length of 50km, we built a secure key between four parties and used it to share an image of the Cheshire cat. It won’t be long before the first quantum-secure Zoom call!

See the original publication in Science Advances or media coverage in the journal Nature and Physics World magazine for more details.

Congrats Euan and Dylan!

We’d like to congratulate Euan Mackay and Dylan Danese, who recently finished their senior undergraduate projects in our research group.

Euan is going on to do his MSc in Theoretical Physics at the University of Edinburgh, while Dylan is continuing onto the integrated MSc in Physics at Heriot-Watt.

Best of luck to you both!

PRL: Genuine High-Dimensional Quantum Steering

Theory and experiment coming together to demonstrate genuine high-dimensional quantum steering.

Our new paper “Genuine High-Dimensional Quantum Steering” has been published in Physical Review Letters. Collaborating along with the Quantum Information Theory Group at the University of Geneva, we formulated simple two-setting steering inequalities, the violation of which certifies a lower bound on the dimension of entanglement in a one-sided device-independent setting.

We experimentally certified 15-dimensional steering in dimension d = 31. It is the highest dimension of entanglement ever certified in a one-sided device-independent setting, which unlocks the potential of high-dimensional entanglement in several applications such as semi-device-independent quantum information protocols. More generally, this represents an important step towards the realization of noise-robust, high-capacity quantum networks in the near future.

npj Quantum Info: Flexible semi-device-independent randomness

A Europe-wide collaboration: With colleagues in Czech Republic, Slovakia, Austria, Poland and Spain, theory and experiment came together for the development of a quantum random number generation framework that can be applied in a wide range of physical scenarios.

Our new paper “Semi-device independent random number generation with flexible assumptions” has been published in npj Quantum Information. Working along with theorists all over Europe, we formulated a framework for semi-device-independent quantum random number generation, and demonstrated the protocol with an experiment in the BBQ Lab. Our approach works with flexible assumptions and different levels of trust, allowing it to be implemented over a large number of practical situations.

This work was the result of an international collaboration that involved people in 6 different countries. Even though some of the co-authors haven’t even met in person, we developed theoretical methods and showed their experimental realisation. This is the power of science: joining people together, even during these difficult times!

AVS Quantum Science: Enhancing noise tolerance with high-dimensional entanglement

Our article “Is high-dimensional photonic entanglement robust to noise?” was featured on the cover of AVS Quantum Science’s first issue of 2021

Our paper “Is high-dimensional photonic entanglement robust to noise?” has been published as a Featured Article in AVS Quantum Science, and is now on the cover of the journal’s first issue of 2021!

Working in collaboration with the HWQuantum group at Heriot-Watt University, we show that the noise tolerance of high-dimensional entanglement can be significantly enhanced. Answering the question “Is high-dimensional photonic entanglement robust to noise?” involves the complex interplay between the characteristics of the quantum state, the channel, and the detection system. In our work, we provide easily measurable experimental parameters that accurately predict system performance and noise bounds, so that the optimum entanglement measurement strategy can be chosen. This works demonstrates the potential of high-dimensional entangled states in the realisation of entanglement-based communication systems under extreme noise conditions.

For some media coverage of this work, please see this AIP Scilight article.