Nature Physics: Unscrambling Entanglement

A chaotic speckle pattern that results from light being scrambled by a complex medium such as a multimode optical fibre. (Image credit: M. Malik and S. Goel)

In new work from our lab published in the journal Nature Physics, we demonstrate how high-dimensional entanglement can be transported through a complex medium consisting of a commercial multi-mode fibre supporting hundreds of spatial modes. This work was done in collaboration with Dr. Hugo Defienne from University of Glasgow.

In a quantum twist, the transmission matrix of the fibre was measured by mapping the entire matrix onto a single entangled state, which is an example of state-channel duality in quantum mechanics. Furthermore, the entanglement was regained without ever manipulating the fibre or the photon that entered it. Instead, we carefully scrambled the entangled partner that remained outside, allowing us to transport 6-dimensional entanglement through the fibre!

Popular media coverage: BBC News, Physics World, Physics Today, Heriot-Watt press release

N. H. Valencia, S. Goel, W. McCutcheon, H. Defienne, & M. Malik, Unscrambling Entanglement through a Complex Medium, Nature Physics (2020), doi: 10.1038/s41567-020-0970-1.

arXiv: Pixel Entanglement in 55 dimensions!

A 97-dimensional pixel hologram used in the experiment and two-photon correlation data

In a record-breaking result from our lab, we recently demonstrated the generation and certification of photonic high-dimensional entanglement with the highest quality, fastest measurement speed, largest dimensionality, and the most “entangled bits” of information till date!

We achieved this through several breakthroughs in theory and experiment, including a cleverly designed spatial-mode basis of macro-pixels and an efficient entanglement witness developed in collaboration with our colleagues in Austria and the Czech Republic. This result demonstrates that high-dimensional entanglement can indeed break out of the confines of an optical laboratory and enable practical, high-capacity quantum communication networks in the near future.

Preprint: N. H. Valencia,  V. Srivastav, M. Pivoluska, M. Huber, N. Friis, W. McCutcheon, and M. Malik, “High-Dimensional Pixel Entanglement: Efficient Generation and Certification,” arXiv:2004.04994 (2020).

Welcome Saroch!

We are excited to welcome the newest member of our group, Dr. Saroch Leedumrongwatthanakun! Originally from Thailand, Saroch recently completed his PhD in the group of Prof. Sylvain Gigan at the Laboratoire Kastler Brossel (LKB) in Paris.

Saroch joins us at a crazy time for science, albeit the world, but it won’t be long before we can put his expertise in complex quantum photonics into action!

Teleportation and a bag of chips

An optical microscope image of the Silicon chip used in the experiment.
Image credit: Llewellyn et al, doi: 10.1038/s41567-019-0727-x

In a recent collaboration spanning Bristol, Denmark, Austria, and China, we demonstrated the teleportation of quantum states of light across two millimetre-scale Silicon chips and the on-chip entanglement of four photons in a GHZ-entangled state. Together with the Huber group at IQOQI Vienna, our team developed efficient theoretical techniques for measuring the generated multi-photon entangled states. These results open the door towards CMOS-compatible quantum technology applications in networking and computation.

Publication: D. Llewellyn et al, “Chip-to-chip quantum teleportation and multi-photon entanglement in silicon,” Nature Physics 16, 148–153 (2020).

PRX: Entanglement beats the Noise

Artist’s depiction of entanglement surviving the onslaught of noise!
(Image credit: Harald Ritsch for IQOQI Vienna)

In our new paper on “Overcoming Noise in Entanglement Distribution” co-authored with colleagues in Austria, Finland, Germany, and Canada, we demonstrate how high-dimensional entanglement in the spatio-temporal degrees of freedom allows one to tolerate large amounts of noise that would generally lead to a loss of qubit, or two-dimensional entanglement. In other words, we certified entanglement with the laboratory lights on! This works demonstrates the potential for high-dimensional quantum states to not only enable high-capacity quantum networks, but also operate in realistic environmental conditions, such as in broad daylight or alongside classical data traffic. For more information, please read this APS synopsis.

Popular media coverage: Heriot-Watt press release, Wiener Zeitung,
Journal reference: Ecker et al, Phys. Rev. X 9, 041042 (2019), doi: 10.1103/PhysRevX.9.041042.