After working with researchers from the National Optics Institute of Italy, University of Rome “La Sapienza” and from the University of Sevilla, two researchers from CEFOP published a paper about high-dimensional quantum systems in Physical Review Letters.
Imagine you have a switch to turn light on or off. It has two perfectly distinguishable possible dimensions: on and off. Now if you have a physical system on a subatomic level, is there any method to know its dimensions without a previous definition?
This question was resolved by Quantum Optics researchers in CEFOP. They established a device-independent method to avoid assuming the dimensions in a quantum system, which at least, can be scaled up to 13 dimensions.
Indeed, in this publication “Device-Independent Certification of High-Dimensional Quantum Systems” (pdf, 554 kb.), “we worked in an important problem in quantum information processing: the certiﬁcation of the dimension of quantum systems without making assumptions about the devices, using the “Dimensional Witnesses” protocols”, said Dr. Gustavo Moreira Lima and Dr. (c) Johanna Figueroa-Barra, researchers who worked with the physicists Vincenzo D’Ambrosio, Fabrizio Bisesto y Fabio Sciarrino (University of Rome) and Adán Cabello (Universty of Sevilla).
The experiment had two phases: the first one in Chile, where the simulations to calculate all the necessary limits of a Dimensional Witness in particular were performed, supported by Dr. Adán Cabello from Sevilla. “This stage required the use of computer programs and simulations with algorithms that we developed from other simulations”, said Johanna. Then, the data was sent to Italy to Dr. Fabio Sciarrino’s team. They were focused on experimental work on a 6-dimensional quantum system (qusixt).
“Experimentally, we studied different certifying protocols for the function of a physical system and we discovered that we could theorize without previously defining the dimension of the system, certifying it during the measurements,” explained Johanna Figueroa.
Often, this protocols are restricted to work with few dimensions at the laboratory (2 or 3), however this experiment allowed to reach 6 dimensions. “That condition gave us the opportunity to publish in a major magazine, which in this case is Physical Review Letters. We are now able to perform simulations and experiments on higher-dimensions and we have proved that the same method can be scaled at least up to dimension 13” said the young researcher.
In Physics, the certification of quantum systems is a topic developed since 2008 and CEFOP begins to approach it with this publication. By July 2014, Dr. Gustavo Lima has committed a visit to Italy and Johanna Figueroa will attend to conferences on this area, in order to deepen her doctoral studies.