Research

• Distributed quantum information processing using atom-plasmon coupling

We aim to create strong electromagnetic coupling between neutral-atoms and localized Plasmons. We are setting up a new experiment to create and use ultracold samples of Strontium atoms for coupling to Plasmonic nanostructures. We aim to experimentally demonstrate these ideas proposed by other groups where it has been shown that, one can achieve strong coupling between atomic two level systems and nano-structures. Currently a setup is being built through funding from Department of Science and Technology to cool and trap Sr atoms. Parallely, we have designed and fabricated silver nanostructures for creating near field optical potentials and these near fields have been measured. The measurements are being validated against numerical simulations. Fig: A) Shows the conceptual schematic of the trapping potentials generated by the nano-disks B) Shows an SEM image of the fabricated silver nanodisks c) Shows an NSOM image of the light field (Image taken at Prof. Achanta Gopal's Group in TIFR, Mumbai)


• Demonstration of Laboratory Prototype of a Gravimeter based on atom interferometry with Bose – Einstein Condensate (BEC)

At the Atomic Physics and Quantum Optics laboratory of IISER Pune, we have successfully built a BEC-based atom interferometer for measuring the gravitational acceleration in Pune. Currently, our experimental setup is capable of measuring the gravitational acceleration with a sensitivity of 1 ppm. Our immediate goals are to translate this system into a portable device and to push the sensitivity beyond ppb. This system also has the potential for measurement of inertial rotations precisely. Atom interferometer is a tool for precise measurement of gravitational acceleration, inertial sensing, magnetic field gradient measurements, and the fundamental physical constants very precisely. The accuracy of AI can go below 1 ppb (parts per billion) in a very compact size compared to an optical interferometer. This development is above TRL level 5 and will be translated into portable system through incubation of startup for translation and commercialization into product. Fig: Atom interferometer signal for measurement of local gravitational acceleration


• Quantum chaos experiments with atom-optics kicked rotor

Superimposing a pulsating 1-D optical lattice onto a sample of ultracold atoms, an Atom-Optic Delta-Kicked Rotor System is being simulated. This work is being carried out in collaboration with the theory group of Dr. M.S. Santhanam (IISER-Pune) In APQO Lab, we use cold atoms to simulate quantum kicked rotor (QKR) to study the quantum chaos. A phenomenon called dynamical localization in QKR is equivalent to Anderson localization. QKR Hamiltonian can be mapped in Anderson Physics so we use it as quantum simulator for Anderson physics. Anderson Metal-Insulator Transition and other condensed matter phenomena can be easily simulated in QKR system. Currently, we are using this QKR system to tune the localization length (a parameter of dynamical localization) that will give us an insight that how much one can tune any quantum mechanical parameter without adding decoherency in quantum system. Fig: Schematic of the atom optic kicked rotor and the kick sequence for different Lèvi exponents. Figure taken from Nonexponential Decoherence and Subdiffusion in Atom-Optics Kicked Rotor


• Atom interferometry with Rb BEC

An atom interferometer is a ubiquitous tool for measuring fundamental constants and inertial sensing. Traditional atom interferometers use a cloud of ultra-cold atoms, howeeve a Bose-Einstien condensate(BEC) can further improve the readout of the interferometer. The thermal atom based interferometers also suffer from Dick effect, which limits their ability to probe slow variations in a physical parameter. We are working on an alternative to reduce the dead time of the interferometer by setting up light gratings which split and recombine an atom laser splilled from a ⁸⁷Rb BEC reservoir, thus enabling a near continuous read-out. We have deomonstrated the first step in this endevour by diffracting an atom laser using a pulsed light grating. The population in different diffraction orders can be controlled precisely by controlling the ON-time of the lattice. Figure taken from Diffraction of an atom laser in the Raman-Nath regime






• Optical atomic clock based on the narrow linewidth transition in neutral Strontium

Atomic clocks based on optical narrow linewidth transitions are paving way for the next generation of time standards. Several of these are already considered as a secondary time standards in International system of units (Le Système International d’Unitès). The relative error in frequency of such clocks is in the 10^-19 regime. We plan to set up an optical lattice clock based on the 689 nm narrow linewidth transistion in neutral Strontium. Such lattice clocks have negligible uncertainty that is introduced due to light shift of the trapping dipole beams when the wavelength of the trapping light used is carefully considered (magic wavelength). Fig: Blue MOT beams at 461 nm.


• Optical tweezer experiments


• Gravitational wave astronomy and physics in collaboration with IUCAA