Theory and Experiment

Research
We are at present concentrating on two broad themes of research.

1. Fundamental tests of quantum mechanics

Quantum mechanics is a cornerstone of modern physics. Just as the 19th century was called the Machine Age and the 20th century the Information Age, the 21st century promises to go down in history as the Quantum Age. However, can we really claim to fully understand quantum mechanical principles? How much do we really believe of what we know? Answers to such questions require us to revisit the fundamental postulates of quantum mechanics and perform precision theoretical and experimental investigations to come up with the right bounds. In our group, a part of our focus is to attempt such investigations using single light particles i.e. single photons as our tools. Such tests carry a lot of importance in the current theoretical physics scenario where a lot of importance is being given to unification of quantum mechanics and general relativity. Such unification attempts would also be benefited if one can have a more precise understanding of the principles involved in at least one of the theories i.e. quantum mechanics.

2. Quantum Information and Quantum Computation

The main thrust of our lab is research on aspects of quantum information and quantum computation. Our systems of choice are qutrits, based on spatial degrees of freedom of the single photon. Our lab is one of the first labs in the country to develop the technology of single photon sources based on spontaneous parametric down conversion in bulk non-linear crystals. We use the single photons and their various degrees of freedom to investigate aspects of quantum optics and quantum information.

Photons are massless, chargeless particles and as such perfect for communication purposes. In the near future, we wish to enter the domain of quantum communication and develop both terrestrial and satellite based technologies.

Location: 

C. V. Raman Avenue Sadashivanagar
Bengaluru
India
IN

Location: 

Hefei and Shanghai
China
CN

The Institute for Quantum Computing (IQC) is a scientific research institute at the University of Waterloo. The research happening at IQC harnesses the quantum laws of nature in order to develop powerful new technologies and drive future economies.

Location: 

200 University Ave. West
Waterloo
Canada
CA

Quantum Science and Technology (QSciTech) supports wide-ranging research programs (theoretical and experimental) aimed at furthering our understanding of the quantum world, and harnessing its unique capabilities to innovate technological advances that would be impossible by other means.

Location: 

Sydney
Australia
AU

The Quantum Optics Group of INRIM performs research both experimental and theoretical, devoted to the investigation of entanglement in quantum mechanics and its application to quantum technologies, such as quantum information processing and quantum metrology. More in detail, many experiments, based on the use of entangled pairs of photons, are being performed, using the "Carlo Novero " eight laboratories (devoted to the memory of Carlo Novero, who began this activity). Among them:

1. We have carried out some experiments concerning Foundations of Quantum Mechanics. In particular, we tested specific local realistic models with Bell inequalities-like experiments. We also performed research aimed at the study of the bounds of quantum correlations. An experiment on wave-particle duality was realized with various optical states as well. This activity was done in part in collaboration with Turin University. Experiments on single-photon quantumness has been carried on in collaboration with NIST and University of Geneva. Finally, an experiment aimed at visualizing Page-Wootters emergence of time phenomenon has been realized in collaboration with Pavia and Pisa Universities.

2. We partecipated to the realization of the first Italian prototype of an entanglement based quantum cryptography link in the framework of a national research program leaded by Elsag Datamat. In this context we investigated quantum key distribution and quantum secure direct communication protocols both theoretically and experimentally based on entangled photon pairs. Furthermore, we realised QKD protocols based on orthogonal states (Goldberg-Vaidman's and controfactual ones). At the moment, we are studying both quantum communication channel (fibre/open air) effects and the realisation of innovative protocols. We participate in the ETSI work group on QKD standardization.

3. Our group also investigates absolute photodector calibration using correlated photons. Beyond studies on the traditional PDC scheme, alternative methods have been developed in collaboration with Moscow University. More recently researches dealt with the calibration of analog detectors.

4. We carried out the study of quantum states engineering, such as the realisation and characterisation of PDC sources with specific properties (also realised in microstructured materials, such as PPLN crystals and waveguides), and the study of entanglement coupling and propagation in fiber. We are also studying entanglement measures and other quantumness quantifiers of quantum optical states. Also specific investigations on peculiar properties of Gaussian states have been carried on. These activities were partially realized in collaboration with Max Planck Institute for the Science of Light and with Milan University.

5. We studied and realised single photon detection systems prototypes with reduced deadtime, exploiting multiplexing based on active optical switch (in collaboration with NIST). We worked on the characterisation of TES detectors (in collaboration with Milan University). Ancilla assisted calibration of photon-number-resolving detector characterisation has been performed in collaboration with NIST.

6. We addressed the reconstruction of photon statistic and, more recently, of the full density matrix by using on/off detectors (in collaboration with Milan and Insubria Universities). Studies on the optimality of tomographic protocols and on the tomography of POVM were realized in collaboration with Moscow and Milan Universities. A novel method for optical field modes reconstruction was developed in collaboration with NIST.

7. We performed studies on the connection between Quantum Imaging and entanglement. After having realized the first Sub-Shot-Noise Quantum Imaging experiment, we also built the first setup in which Quantum Illumination was achieved. Also activities on ghost imaging have been carried out. Now we are considering the advantages of these techniques in interferometry (e. g. for the holometer, i.e. a double Michelson interferometer aimed at testing quantum gravity). Some of these works were in collaboration with Milano University and Insubria University.

8. We realized an extremely low-noise heralded-single-photon-source (based on PPLN crystal) that does not need temporal post-selection for the emitted single-photon in collaboration with NIST and Polytechnic of Milano. Coupling enhancement of single photon sources based on impurities in diamonds by micro- and nano-structures is an on-going activity carried on in collaboration with Turin University.

9. From a theoretical point of view we worked on multidimensional QKD, application of mesons to local realism tests and quantification of quantum correlations (with Torino University, Politecnico and ISI).

Location: 

Strada delle Cacce 91
Torino
Italy
IT

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