Home Page Researchers Hagai
The Racah Institute of Physics
Faculty of Science
The Hebrew University of Jerusalem, 91904, Israel
Tel: +972-2-6585228; Fax: +972-2-6512483
Quantum Optics with Multi-photon States
One of the great mysteries in the way we understand the physical world is a quantum mechanical phenomenon called "entanglement". Entanglement is a manifestation of a basic property of the physical world that is against our everyday experience. We are used to the notation of an object occupying a specific position, but in the quantum world of the very little, as long as we do not try to check the object's position, it is "non-local" - it's exact position is not well defined but can be many positions at the same time. One of the consequences of this non-locality is that a few quantum objects can exist together in the same "quantum entangled state" even if separated by a great distance.
The generation and study of "entangled quantum states" is crucial for understanding the foundations of our perception of the physical world. In the last 30 years, as technology advanced and enabled these studies, more and more experiments involving entangled quantum states where done. Entanglement has been shown to be a very useful resource in the field of "Quantum information". In this approach, information is stored inside the state of quantum system instead of in a classical computer memory. The manipulation of these so called q-bits (quantum bits) is very efficient and it was shown that for some computational problems, a "quantum computer" can exceed the speed of standard computers by many folds. Another demonstrated use for qubits is the ultimately secured communication line - quantum cryptography.
Entangled states of a different form have been shown to be useful to defeat other physical limitations. In the computer chips industry, companies like Intel are limited by the wavelength of light to how many components can be placed in one computer processor. Quantum photo-lithography was suggested as a method that uses quantum entangled light to record denser components on every chip. This method was demonstrated in principle, but it still awaits a few technological improvements.
As the number of entangled particles involved in these peculiar states is increased, the boundaries between the quantum reality and our everyday world are being probed. Entangled states of many particles also increase the number of possibilities for their various uses. Recently, states with up to 14 particles were produced and studied, but as the particle number increases, the harder it is to create the state.
We study experimentally the effects of using multi-photon entangled states on the various uses of quantum information. To do so, we will also need efficient new sources of entangled optical states. Such states will also be useful for quantum photo-lithography.
Specific Research topic related to Nanoscience and Nanotechnology:
- Quantum limited measurements
- A single photon on-demand source using a surface wave plasmonic collimator
Significant publications in the last five years:
- "A resource efficient source of multi-photon polarization entanglement", E. Megidish, T. Shacham, A. Halevy, L. Dovrat and H.S. Eisenberg, Phys. Rev. Lett. 109, 080504 (2012).
- "Realizing a variable isotropic depolarizer", A. Shaham and H.S. Eisenberg, Opt. Lett. 37, 2643 (2012).
- "Measurements of the dependence of the photon-number distribution on the number of modes in parametric down-conversion", L. Dovrat, M. Bakstein, D. Istrati, A. Shaham, H.S. Eisenberg, Opt. Express 20, 2266 (2012).
- "The biaxial nonlinear crystal BiB3O6 as a polarization entangled photon source using non-collinear type-II parametric down-conversion", A. Halevy, E. Megidish, L. Dovrat, H. S. Eisenberg, P. Becker and L. Bohat?, Opt. Express 19, 20420 (2011).
- "Projection of Two Biphoton Qutrits onto a Maximally Entangled State", A. Halevy, E. Megidish, T. Shacham, L. Dovrat, and H. S. Eisenberg, Phys. Rev. Lett. 106, 130502 (2011)
New patents and patents utilization (2011-2012):
- a variable isotropic depolarizer
Cooperation with industries and defense projects (2009-2010):
MAFAT funded activity on "low photon number communication" and "single-photon on-demand sources"
Cooperation with other researchers/universities in Israel:
Within Hebrew University:
With other universities:
- Prof. Michael Ben-Or and Prof. Dorit Aharonov, Computer science Dep.
- Prof. Yossi Paltiel, Prof. Ronen Rapaport and Prof. Uriel Levi
- Prof. Ady Arie, Electrical Engineering Dep., Tel-Aviv University
- Ministry of Defence, ?Sparse photon communication?
- Ministry of Defence, ?A Single photon source system?, Yossi Paltiel, Uriel Levy and Ronen Rapaport (HUJI)
- Israel Science Foundation Bikura project, ?Room temperature single photon on-demand sources based on a plasmonic lens?, Yossi Paltiel and Ronen Rapaport (HUJI)
- Israel Science Foundation, ?A scalable photon entanglement source?
Students, postdocs and researchers (include those graduated in 2009-2010):
Post-docs: Noa Voloch-Bloch
Ph.D. students: Eli Megidish, Assaf Halevi, Assaf Shacham
M.Sc students: Daniel Istrati, Lior Cohen, Yehuda Pilnyak
Copyright © The
Hebrew University of Jerusalem