(A1)-PROJECT-1

Nobel Prize to Bloembergen-Schawlow-Siegbahn

Nonlinear Optics & Laser Spectroscopy of Atoms & Molecules

CLICK-(NOBEL-PRIZE-1981)

PROJECT-1

(P. S. Bhatia)

Nonlinear Optics-EIT-Slow Optical Pulses

-Ultra-Cold BEC Atom

-Quantum Information

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PROJECT-1

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An experiment is a question, which science poses to nature

and measurement is a recording of nature’s answer.

----- Max Planck

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Click For: Electromagnetically Induced Transparency (EIT)

Figure Below shows Slow Optical Pulse

After Krauss, Nature Photonics 2, 448 (2008).

Research Overview

Physical origin of optical nonlinearity is the quantum mechanical perturbation of valance electrons of the material medium by electric field of strong optical beam incident on the medium and nonlinear susceptibility represents the an-harmonic term in the expansion of the dielectric polarization induced by strong optical field in the medium. Therefore, due to perturbative nature of underlying process, magnitude of nonlinear susceptibility is extremely weak and is orders of magnitudes weaker than linear susceptibility. Therefore, strength of nonlinear signal (or alternately generation efficiency) of any nonlinear optical process, which depends on magnitude of nonlinear susceptibility, is also extremely weak. This is the major drawback of traditional nonlinear optics. Nonlinear optical processes are used in many-many practical applications. Therefore, enhancement of magnitude of nonlinear susceptibility is of very high practical importance.

Past and original work on enhancement of magnitude of nonlinear susceptibility, which was done by N. Bloembergen at the Harvard University, was based on technique of Resonance Enhancement. This research led to Nobel Prize for year 1981, which was awarded to N. Bloembergen (Harvard) and A. Schawlow (Stanford) (CLICK-(NOBEL-PRIZE-1981)). Recent availability of new techniques of EIT, slow optical pulses, and cold-atom technology provides opportunity to further greatly enhance magnitude of nonlinear susceptibility and generation efficiency of nonlinear optical processes.

Electromagnetically Induced Transparency (EIT) is a quantum interference effect (M. Fleischhauer et al., Rev. Mod. Phys. 77, 633 (2005)) and Slow Pulse is an optical pulse (R. W. Boyd et al., Science326, 1074 (2009)), which propagate with group velocity far less than usual speed of light (c) . Both EIT and slow pulse were invented by Stephen E. Harris at the Stanford University. Although, EIT and slow pulse have found many practical applications (J. B. Khurgin and R. S. Tucker, Eds., Slow Light Science and Applications (Taylor & Francis, 2008)) but enhancement of nonlinear optical effects is one of the most important application of electromagnetically induced transparency (EIT) (S. E. Harris et al., Phys. Rev. Lett. 64, 1107 (1990); Phys. Rev. Lett. 93, 183601 (2004); J. D. Joannopoulos et al., Nature Material 3, 211 (2004)) and slow pulse (S. E. Harris et al., Phys. Rev A 68, 041801 (2003); Phys. Rev. Letts. 82, 4611 (1999); C. Monat et al., Opt. Express 17 (4), 2944 (2009)).

In this project we use multiple EIT strong dressing fields and multiple slow optical pulses to enhance extremely weak magnitude of nonlinear susceptibility. This enhancement is further greatly increased in ultra-cold condensed BEC atoms, so that nonlinear interaction between single cold atom and single-photon pulses can be experimentally realized. Our recent investigations using EIT and slow pulses predict very huge enhancement (see Figure below) of magnitude of nonlinear susceptibility of ultra-cold atoms, which is orders of magnitude greater than any previously reported enhancement of nonlinear susceptibility. This project eliminates major drawback of traditional nonlinear optics and push light-matter interaction to a new regime where nonlinear optical processes can be practiced with almost same generation efficiency as linear optical processes ! Therefore, this project totally revolutionize light-matter interaction & can bring next Nobel Prize. This research is important for Heisenberg limited high-sensitive and high-resolution nonlinear spectroscopy of ultra-cold atoms & molecules. In this project we also study nonlinear optical properties of BEC as a new condensed matter material. In addition, this research is useful for development of atomic size nonlinear photonic devices and for designing nonlinear optics based atomic size quantum logic gates require for building next generation of quantum computer.

Above Figure Shows Our Recent Result:

Huge Increase in Magnitude of Third-Order Nonlinear Susceptibility of Ultra-Cold BEC Atoms with Electromagnetically Induced Transparency (EIT)

More Detailed Description of this Project

Title: Enhancement of Nonlinear Optical Effects in

Ultra-Cold BEC Atoms & Molecules

Using Quantum Interference Effects

(With Electromagnetically Induced Transparency (EIT) and Slow Light Pulses)

Abstract: This project integrates four different areas of research, which are: (1) Nonlinear Optics (NLO), (2) Quantum Interference /EIT & slow light pulses, (3) Bose-Einstein Condensation (BEC), & (4) Quantum Information Science (QIS). In this project using combination of resonance enhancement, cold-atom BEC technology, slow and compressed optical pulses, quantum entanglement, and low-light level quantum limited detector technology, we aim to enhance generation efficiency and detection sensitivity (i.e. signal-to-noise (S/N) ratio) of nonlinear optical processes. In this four-wave mixing (FWM) experiment, which is based on third-order nonlinear interaction, all three input optical pulses are tuned to resonant transitions of ultra-cold atoms/ molecules and resonant absorption is cancelled by quantum interference effect. Experimentally feasible novel techniques for simultaneously slowing three optical pulses and matching their group velocities in ultra-cold nonlinear atomic medium are presented. All three ultra-slow propagating pulses are finally compressed in space so that spatial length of these pulses matches with the physical length of the ultra-cold nonlinear atomic medium. This results in very huge increase in the strength of generated nonlinear signal so that extremely low light level signal generated by third-order nonlinear susceptibility (Chi-3) of a single cold atom with magnitude as weak as 10^-27 (10 raise to the power - 27) esu can be detected (Ultra-Giant Kerr effect). This high-sensitive and extreme cared experiment requires development of very sophisticated and large-scale experimental facility in which almost every optical component is special purpose. Major hardware developments required for this experiment include creation of Cesium (Cs) BEC in a dipole trap, development of injection seeded solid-state laser system that generates highly stable narrowband optical pulses tunable both in frequency and pulse-width, high precision wavemeter that can monitor operating characteristics of light pulses with frequency measurement accuracy of the order of 1 part in 10^10 (10 raise to the power +10), ultra-low noise photo-detector for pulsed measurements that can achieve noise level below the standard quantum limit, and computer controlled gated data acquisition system based on fast electronics. This project provides first and original investigation of strong field light-matter interaction in the nonlinear regime and at ultra-low temperature. This research is important for Heisenberg limited high-sensitive and high-resolution nonlinear spectroscopy of ultra-cold BEC atoms/ molecule. Further, this research paves the way towards new era of quantum information technology in which atomic size nonlinear photonic devices are likely to operate by nonlinear interaction between single atoms and single photons. Such photonic devices are needed for development of real-world practical quantum logic gates and quantum processors required for quantum computation.

Above Figure Shows Schematic of Experimental Apparatus for Study of Nonlinear

Optical Properties of Ultra-Cold BEC Atoms using EIT & Slow Optical Pulses

(Large-Scale Experiment

Above Figure Shows

Electromagnetically Induced Transparency (EIT)

Observed in Cesium (Cs) Atom

(After: Bhatia et al.,

Opt. Commu 189 (4-6), 321 (2001))

Above Figure Shows Scheme for High-Precision Measurement of Sub-Natural EIT

Resonances in Ultra-Cold Atoms & Molecules using Slow Optical Pulses

Precision Measurement Accuracy: 1 Part in 10^ 10 (Ten raise to the power Ten)

(After: Bhatia et al., Appl. Opt. 38 (12), 2486 (1999).

Above Figure Shows High-Sensitive Detection Scheme for

Quantum Noise Limited Detection at the Heterodyne Photo-Detector

Brief Description of this Project:

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Publications & Presentation Related to this Project:

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