Research

At IIT Tirupati we are primarily focusing our research activities in two completely diverse directions: quantum communication and metrology, while the other direction is geared towards precision laser spectroscopy of low temperature plasmas. We shall set up experiments along both research directions to establish new techniques to understand fundamental properties of quantum matter systems.

Hybrid Quantum Networks - A new pathway to decoherence-free, long distance secure quantum communication

At IIT Tirupati we are spearheading efforts towards establishing a hybrid quantum network for decoherence-free, secure, long distance communication based on a hybrid platform that comprises of an atomic as well as a solid-state quantum node. These quantum nodes communicate with each other through exchange of single photons. The development of hybrid quantum networks has been a new pathway that claims to combine the best of both worlds: fast read-out from quantum bits comprised of atoms and storage of quantum information in solid-state counterparts like color/vacancy centers in silicon (Si) or diamond (C). We firmly believe that hybrid quantum networks may provide opportunities and challenges across a range of technical frontiers including quantum computation, quantum communication and metrology. We hope that such hybrid quantum networks may pave the way for perfectly secure data transmission and enhanced data processing via distributed quantum computing .

Some possible scientific goals of the above research directions:

Single photon generation from ion trap cavity QED system

Single photon generation from NV centers in diamond

Atomic clocks and frequency metrology

Measurement of time and frequency have always been closely linked with the development of human civilization. Precise time measurement is critical to a lot of applications - communication, navigation and position mapping. Frequency and time are the most precisely measurable physical quantities. This has led to a complete overhaul of the SI (Metric system) with all fundamental SI units being linked to the measurement of time.

Current day GPS techonology relies on atomic clocks on-board a GPS satellite. India's own NAVIC system imports space grade atomic clocks for its GPS satellites. One of the major objectives of this project, is to drive the growth of indigenous portable atomic clocks for space and civil applications. Atomic clocks find their use not only in navigation and position sensing, but in defense and aerospace, banking, space and land geodesy, VLBI, and oil and mineral exploration. 

As Atomic, Molecular and Optical Science and Technology is one of the focus areas of IIT Tirupati, the current project on developing atomic clocks is in sync with the thrust area. Further, IIT Tirupati was awarded a Technology Innovation Hub (TIH) on Positioning and Precision Technologies (PPT) under the National Mission on Interdisciplinary Cyber Physical Systems (NM-ICPS). The propsed project on developing portable atomic clock technology is thus well motivated to align with the goals and objectives outlined for the TIH in PPT.  We are also collaborating with research groups in ISRO, IUCAA Pune, IISER Pune and the RRI Bengaluru in this project.

We are currently pursuing two directions to develop atomic clocks.

• One is a trapped ion atomic clock. For this we have chosen a Calcium (40Ca+) ion as our target species. Calcium ion has a clock transition at 729 nm. This shall be an optical clock. 

• The other is a vapor cell based atomic clock that relies on coherent population trapping (CPT) phenomenon to drive a clcok transition between the two ground states of Rubidium (Rb) atom. This will be microwave transition based clock. We have been awarded an SERB SRG grant to inititate activities on this project.

                                                Schematic of Calcium ion energy level diagram [Left] and Paul (ion) trap [Right]. 

[Left image] Schematic of CPT interaction scheme for an alkali atom. Solid arrows indicate the light frequencies ν1 and ν2.  Δ0 is the optical detuning and δR is the Raman detuning. νhfs is the ground state hyperfine slitting for the alkali atom. [Right image] Shows the CPT resonance with a narrow linewidth of ~ 1kHz.

Precision laser spectroscopy of cold plasmas

In collaboration with our Departmental colleague Dr. Reetesh Kumar Gangwar, we are planning to develop "a cavity based precision spectrometer" for spectroscopic analysis for diverse atoms, molecules, and chemical compounds. We are also fortunate to collaborate with Dr. Saikat Chakraborty Thakur, Associate Project Scientist, Center for Energy Research, UC San Diego, USA and Dr. Amar C. Vutha, Asst. Professor, Department of Physics, University of Toronto, Canada on this project. The proposed instrument and the potentially diverse applications ranging from "environmental to biomedical to fundamental physics problems". 

The above spectrometer is based on a sophisticated technology called cavity ring down spectroscopy (CRDS). CRDS techniques were proposed way back in the 1980s and have since come a long way.  Some potential applications of cold plasma technology in food industry: Microbial inactivation and toxin degradation in food products, and also for food packaging materials modifications. 

As the food processing and environmental remediation are the thrust areas of the IIT Tirupati and the cold plasma research can contribute significantly in these areas, it is well established now that cold plasma has great potential. However it comes with its own unique challenges. One of the biggest challenge is to scale up the technology to a commercial scale. This essentially requires the optimization of plasma-based processing in a specific application. In order to optimize the processing, a deep understanding of plasma surface interaction is required. This fact becomes more crucial if the target surface is heat sensitive such as food. The processes needed to be non-thermal to ensure food quality after the treatment. To understand the plasma surface interaction, the development of advanced spectroscopic diagnostic schemes is needed. The proposed FS-CW-CRDS (Frequency stabilized continuous-wave cavity ring down spectroscopy) systems shall be a very good step in this direction.

Depending on the design of the plasma source, cold atmospheric plasma inactivates or reduces

• Bacteria, spores, fungi and viruses

• Bio-films

• Mites and allergens

• Odors – in air streams or textiles (“Electron-Impact-Dissociation” process)

• Harmful molecules in a flow process – e.g. emissions 

Due to the above properties, cold plasmas have applications in different areas of operation: Medical technology, Hygiene, Water treatment, Odor management, Air purification, Emission control.  In addition to the above uses, cold plasmas have also been effectively used for the following industrial applications:

 • Surface hardening of stainless steel

• Surface curing of textiles at low costs

• Surface treatment of polymers and fibers to enhance tensile strength

• Nano-coatings and wood treatment

• Semiconductor etching

 Apart from the above potential industrial applications, a cold plasma based continuous wave cavity ring-down (FS CW CRDS) instrument will be a potential game changer for basic sciences as well. Cold and ultra-cold plasma research is primarily concerned with the fundamental properties of plasma in new parameter regimes, but there is also an active ongoing research exploring their use for the production of very mono-energetic electron and ion beams. Research in ultra-cold plasmas may in the end offer insights into a wide variety of systems, such as plasma propulsion systems, the ionosphere and other astrophysical environments, and inertially confined plasmas for fusion. Till date no one has performed precision laser spectroscopy on cold deuterium plasmas - a key component of fusion plasma reactors.

An important thermodynamic parameter describing plasmas is the ratio of the electrostatic repulsion between the ions to the kinetic energy of the ions. In ultracold plasmas, the interactions between ions are more important for defining the properties of the plasma rather than the motion of the constituent ions. This phenomenon is the hallmark of a “strongly coupled plasma”. It is surprising that this ratio is roughly the same for the high-temperature, high-pressure plasmas that are currently being used in the laser-driven ignition of nuclear fusion. A similar ratio is also found within giant planets such as Jupiter and white-dwarf stars where the crushing force of gravity pushes hydrogen atoms so close together that they form a hot, dense plasma. As a result, ultracold plasmas could be used as simulators that could boost the development of fusion energy sources and improve our understanding of stars and planets.