COPS congratulates alumnus Prof. Jaime Gomez Rivas (Differ) with his VICI grant!
Friday, 24 February, 2017 - 16:46

COPS alumnus prof. Jaime Gomez Rivas is among the recent winners of a prestigious NWO-Vici personal grant for his proposal Strongly Coupled OPtoElectronics (SCOPE). Jaime Gomez Rivas did his Ph.D. research at COPS on Anderson localization of light and defended his thesis in 2002 (click here) . He now leads the "Photonics for Energy" group at the DIFFER Institute in Eindhoven: Congratulations! (Felicitaciones! :-)

Researchers transmit 10 bits of information with a single photon
Friday, 3 February, 2017 - 16:17

COPS researchers at the University of Twente’s MESA+ research institute have managed to transmit more than 10 bit of information with a single photon. They achieved this using an ingenious method for detecting individual photons. The knowledge gained from this study can be used to improve the security and speed of quantum communication. The research results were published today in the scientific journal Optics Express.

When asked “How much information can you transmit using just a single photon?” most scientists would answer ‘one bit’ (either a ‘1’ or a ‘0’). In theory, however, there is no limit to the amount of information you can transmit with a single photon. There are, however, many practical considerations that limit the amount of information per photon. Using an innovative method, University of Twente researchers have now managed to transmit no less than 10.5 bits of information with a single particle of light. 


Prof. Pepijn Pinkse, one of the researchers involved, explains how the system works. “You can compare it to shining a laser pointer onto letters mounted on a groove board. The illuminated letter is the information contained in the laser pointer’s light. The number of letters on the groove board determines the amount of information you can transmit with the light.” The main difference is that Prof. Pinkse and his team created an alphabet of 9072 characters, and they – unlike the laser pointer in the analogy above – transmitted the information with a single photon. That was the key challenge in this study: single photon detection. This is because noise (random photons) can impede measurement. The researchers devised a clever ruse to eliminate any noise. They exploited the fact that individual blue photons can split into exactly two red photons. The researchers arranged for the first photon to send a signal to the detector (which is comparable to a digital camera), which then opened up very briefly. Using a mirror, the second photon was directed at the desired letter of the specially created alphabet. However, they forced this photon to make a slight detour, so that it arrived at the target letter at exactly the same time as the detector opened up. That was the only instant at which photons were able to pass into the detector. In this way, the researchers were able to eliminate noise.

In practical terms, it is difficult to specify the maximum amount of information you can transmit with a single photon, according to Pinkse. “Using our method, there is no theoretical limit to the amount of information that can be sent. The amount of information depends on the size of the alphabet you create. But, even if you could create an alphabet with as many characters as there are atoms in our entire universe, you would still only be able to transmit a maximum of 270 bits with one photon.” 


Prof. Pinkse, who originally made a reputation by developing an unhackable credit card, says that the main objective of this study is to raise quantum communications to a higher level. “The more information you can transmit with photon, the more secure and the faster you can make quantum communication.”

The research published in OSA journal Optics Express entitled "Transmitting more than 10 bit of information with a single photon" was carried out by Tristan Tentrup, Thomas Hummel, Tom Wolterink, Ravitej Uppu, Allard Mosk and Pepijn Pinkse of the Complex Photonic Systems (COPS) and Laser Physics and Nonlinear Optics (LPNO) chairs at the University of Twente’s MESA+ Institute for Nanotechnology. The study was partly funded by the European Union and the Foundation for Fundamental Research on Matter (FOM). 

Willem Vos celebrates 25th anniversary as civil servant
Tuesday, 13 December, 2016 - 15:23

On December 9, 2016, COPS scientist Willem Vos celebrated his 25th anniversary as a civil servant in the Netherlands (a combination of positions at UT, AMOLF, and University of Amsterdam). The wonderful event was celebrated as a high tea party at the "gezellig" Theehuis Sprakel in het Bos. To grace the occasion, many joined in: family, friends, colleages from COPS and UT groups (LPNO guided by Klaus Boller), TNW staff, and the Utrecht LINX group (guided by Allard Mosk). Guests of honor were Prof. Thom Palstra, the new Rector Magnificus of the UT, and Prof. Hans Hilgenkamp, dean of the Faculty of Science and Technology. Highlights were speeches by Pepijn Pinkse and Hans Hilgenkamp about Willem's journey, and an infamous COPS "No-Mercy Production" to poke some fun at the laureate. 



Tom Wolterink awarded degree of doctor
Friday, 25 November, 2016 - 09:35

After succesfully defending his thesis with the title "Programmable quantum interference in massively multichannel networks" on 26 October 2016, Tom Wolterink has been awarded the degree of doctor. The work was carried out in the group of Complex Photonic Systems (COPS) and the group of Laser Physics and Nonlinear Optics group (LPNO) under the supervision of Pepijn Pinkse, Willem Vos, and Klaus Boller.

Thursday, 27 October, 2016 - 15:02

On September 30, COPS bachelor student Willemijn Luiten graduated with a colloquium on her bachelor thesis "High dimensional spatial information encoding in single photons for QKD".