Prelude: Welcome to my homepage. I am a theoretical condensed matter physicist. Here is a brief outline of my research contour.

I have been looking for some highly motivated and very hardworking students with good analytical and numerical (programming) skill who are ready to take up challenging problems in quantum condensed matter. These problems could be in the field of graphene ( including Moire pattern in magic angle twisted graphene multilayers), topological insulators, Weyl semimetals, Floquet systems, Time crystals as well as quantum simulations with ultra-cold atomic gases. The problems in these field are exciting and simultaneously challenging and hard. Thus only students with solid academic background with very good aptitude in mathematics and willing to work very hard for long-period of time with patience need to approach me.

As you may know, quantum mechanics has been driving our understanding about the microscopic world starting from the beginning of the last century. However its effect becomes aprreciable at macroscopic level only if the wavefunction ( some type of probability wave according to the postulates of quantum mechanics) associated with such microscopic constituents of matter interfere. Over last few decades wonderful experimental discoveries brought to us amazing display of such quantum properties in a host of materials, hard as well as soft, at different macroscopic scales. The traditional solid state physics was rechristened as the condensed matter physics and expanded its horizon significantly. Three aspects of this quantum condensed matter world interest specifically our group’s research.

The first is the collection of exotic transport properties, typically clubbed as the quantum transport ( Quantum Hall Effect, transport in Graphene and topological insulators, heterojunctions). The definition of the word “quantum transport” is not very unique, though there are some broad contours. Here I use it in a very loose sense. It aims  to understand such transport properties at some level where you need to solve the effective quantum mechanical equation of the involved charge carriers and then do the relevant statistical mechanics.

The other topic is “Quantum Simulation”, a name inspired by legendary Richard Feynman, by which state of the matter in one type of quantum system is simulated in another quantum mechanical system. We particularly work on quantum simulation with ultra cold atomic systems.

The third topic is topological phases in condensed matter systems. This includes a host of subtopics such as, topological defects in quantum Hall and ultra cold atomic systems, topologically non trivial properties asscoiated with the band structure of Dirac materials such as Graphene and Topological Insulators, Weyl semi-metal, Topological Phases in ultra cold atoms, Floquet systems, Time crystals, Moire bands in magic angle twisted multilayer graphene etc.

The above three topics are not necessarily three disjoint pieces and quite often our effort is to look at the quantum condensed matter system from a broader perspective combining all three above topics.These problems are challenging as well as exciting. They are potent with the possibilities of device ( technological) applications. Apart from Ph.D. projects, undergraduate and master’s projects with minimum commitment for one year are also sometimes available within the frame-work of IIT Delhi. Post-doctoral fellows are most welcome provided they are serious in working for at least two-years with complete focus.

For some interesting recent research results you may look at the following link: “ Study reports a transition from spontaneous to stimulated Hawking radiation in a sonic black hole”

 

                                                                                                                                                                  

Main Research Interest with Selected Publications:

Quantum Hall Systems: During my Ph.D. with my thesis supervisor Prof. R. Rajaraman I worked on Topological Excitations in Bi-Layer Quantum Hall systems. We particularly studied Meron-pairs, Bimerons, Skyrmions, CPN solitons. With my Ph.D. student Dr. Puja Mondal and Prof. Alain Nogaret of University of Bath, UK, we recently worked on the relation between electric and magnetic edge states in magnetically modulated Quantum Hall systems.

1.  Crossover between magnetic  and electric edges in quantum Hall systems: Alain Nogaret, Puja Mondal, Ankip Kumar, Sankalpa Ghosh, Harvey Beere and David Ritchie : Physical Review B, 96, 081302 (R) (2017)

2. Quantum Transport through pairs of edge states of opposite chirality at electric and magnetic boundaries: Puja Mondal, Alain Nogaret and Sankalpa Ghosh : Phys. Rev. B, 98, 125303 (2018)

3. Quantum Hall solitons with intertwined spin and pseudospin at  ν=1 :  Sankalpa Ghosh and R. Rajaraman : Phys. Rev. B 63, 035304 (2000)

Ultra Cold Atoms and Bose-Einstein Condensation: Starting from my post doctoral years I worked on several aspects ultra cold atoms with a variety of collaborators that includes my post doctoral advisors in Technion, Ph.D. students as well as undergraduate students. Partcularly with Prof. Eric Akkermans and Prof. Z. Musslimani we worked on the disorderd one dimensional interacting Bose-Einstein quasi-condensates and discussed the possibility of Anderson localization. This work was prior to the experimental observation of Anderson Localization by Alain Aspect’s group is France. With my Ph.D. student Dr. Rashi Sachdeva ( now in Lund, Sweden) we have worked on the effect of light induced artificial gauge field on the exotic phase of supersolid in an ultra cold atomic systems. With Bikash Padhi ( now in UIUC) we studied the ultra cold atomic in systnetic abelian and non-abelian gauge fields ( such as spin-orbit coupled BEC) places inside an optical  cavity and pointed out how cavity transmission helped to identify phenonema that is analogue to Sdh oscillation in condensed matter systems, and some exotic magnetic phases of ultra cold atoms. Very recently spinorial BEC in optical cavity was experimentally studied by ETH Group led by T. Esslinger. Of late I have been working with my Ph.D. student Ms. Inderpreet Kaur on sonic black holes in spinorial ultra cold atomic systems. With another Ph.D. student Ms. Poornima Shakya I have been working on quantum silumation with ultra cold atoms in a cavity.

1. (2+1)-dimensional sonic black hole from a spin-orbit coupled Bose-Einstein condensate and its analog Hawking radiation : Inderpreet Kaur and Sankalpa Ghosh, Physical Review A, Vol 102, 023314 (2020).

2. Entanglement-like properties in spin-orbit coupled ultra cold atom and violation of Bell-like inequality : Rahul Kumar and Sankalpa Ghosh, Journal of Physics B : At., Mol. And Opt. Phys., Vol 51, 165301 (2018).

3. Hydrodynamic theory of rotating ultracold Bose_Einstein Condensates in Supersolid phase, Rashi Sachdeva and Sankalpa Ghosh, J. Phys. B At. Mol. Opt. Physics, 48, 105301 (2015).

4.  Spin-orbit coupled Bose-Einstein Condensates in a cavity: Route to magnetic phases through cavity transmission:  Bikash Padhi and Sankalpa Ghosh , Phys. Rev. A 90, 023627 (2014).  

5.  Cavity Optomechanics with Synthetic Landau levels of ultracold Fermi Gas:  Bikash Padhi and Sankalpa Ghosh, Physical Review Letters, Vol 111, 043603 (2013). (Read the paper).

6. Density Wave-Supersolid and Mott Insulator – Superfluid transition in presence of artificial gauge field : Astrong coupling perturbation approach,  Rashi Sachdeva and Sankalpa Ghosh, Physical Review A, Vol. 85, 013642 (2012).

7. Fock-Space exploration by angle-resolved transmission through a quantum diffraction grating of cold atoms in optical lattice: Adhip Agarwala, Madhuriam Nath, Jasleen Lugani, K. Thyagarajan and Sankalpa Ghosh, Physical Review A, Vol. 85, 063606 (2012).

8. Cold atoms  in rotating optical lattice with nearest enighbour interaction: Rashi Sachdeva, Sonika Johri and Sankalpa Ghosh, Phys. Rev. A, Vol 82, 063617 (2010).

9. Numerical study of one-dimensional and interacting Bose-Einstein condensates in a random potential : Eric Akkermans, Sankalpa Ghosh and Ziad H Musslimani, J. Phys. B At. Mol. Opt. Phys., Vol 41, 045302 (2008).

10. Spinor Dipolar Bose-Einstein Condensates: Classical Spin Approach: M. Takahashi, Sankalpa Ghosh, T. Mizushima and K. Machida, Phys. Rev. Lett. Vol 98, 260403 (2007).

11. Quantum tunneling of vortices in two dimensional condensates: Assa Auerbach, D. P. Arovas and Sankalpa Ghosh, Phys. Rev. B., Vol 74,  064511 (2006).

Electron Transport in Dirac Materials ( Graphene, Topological Insulators etc.): Almost for last ten years or so I have been exploring mesoscopic transport in Dirac materials such as Graphene, surface states of Topological insulators, heterojunctions of superconductors with Dirac materials with a host of collaborators and students. With my ex-colleague Dr. Manish Sharma ( now in Samsung) and subsequently with Ph.D. student Dr. Neetu Agrawal (Garg) and research assistant Dr. Sameer Grover( now in Weizman Institute) we explored novel quantum transport in mono and bilayer graphene in presence of inhomogenous and localised magnetic field and one dimensional patterns created by them. We have particularly developed an optical analogy of such transport that gained some popularity in the community and later on also inspired interesting experiments. With my Ph.D. student Dr. Puja Mondal we later on did some studies of quantum transport through the surface states of three diemnsional Topological Insulators in presence of static and time-dependent Electromagnetic field. Our purpose was to see the possibility of device application by exploring novel ballistic transport regimes using such optical analogies. With my Ph.D. student Ms. Manisha Arora we recently considered the electron transport of in monolayer Graphene in presence two-dimensional periodic patterns of non-uniform and localized magnetic field. We particularly showed that in such systems the Hall conductivity is topologically quantized because of the simultaneous existence of conventional Quantum Effect in presence of a uniform magnetic field and Haldane’s anomalous Quantum Hall effect without net magnetic field. Manisha defended her thesis this year and got her Ph.D. degree. Other problems we have working with,( with my Ph.D. student Sharukh Salim and colleague Prof. Rahul Marathe) are the transport in hetero-junctions of Dirac Material. Deepanshu Aggarwal and Disha Arora ( jointly supervised with Prof. Rohot Narula) are working on magic angle twisted graphene bilayers. Partha Sarathi Banerjee ( jointly supervised with Prof. Rahul Marathe) is working on some exotic aspects in Dirac material based composite systems.

1. THz photodetector using sideband modulated transport through surface states of a 3D topological insulator : Puja Mondal, Sankalpa Ghosh and Manish Sharma, Journal of Physics : Condensed Matter, Vol 31, 495001 (2019).  

2. Magnetic Hofstadter butterfly and its topologically quantized Hall conductance : Manisha Arora and Sankalpa Ghosh, Phys. Rev. B, Vol. 98, 155425 (2018)

3. Unconventional band structure for a periodically gates surface of a three-dimensional topological insulator: Puja Mondal and Sankalpa Ghosh, Jour. of Phys., Cond. Matt., Vol. 27 495301 (2015). 

4. Scattering of massless Dirac fermions in circular p-n junction with and without magnetic field: Neetu Agrawal (Garg), Sankalpa Ghosh and Manish Sharma, Jour. of Phys, Cond. Matt., Vol. 26, 155301 (2014).

5.  Electron Optics with Dirac Fermions: Electron Transport in Monolayer and Bilayer Graphene through magnetic barrier and their superlattices:  Neetu Agrawal (Garg), Sankalpa Ghosh and Manish Sharma, International Journal of Modern Physics B, Vol 27, 1341003 (2013). (Invited Review Article: Free to read.)

6. Reversal of Klein Reflection by magnetic barriers in bilayer graphene: Neetu Agrawal, Sameer Grover, Sankalpa Ghosh and Manish Sharma, Jour. of Phys. Cond. Matt., Vol. 24, 175003 (2012).

7.  Electron Transport and Goos Hanchen Shift with electric and magnetic barriers: optical analogy and band structure: Manish Sharma and Sankalpa Ghosh, Journal of Physics Condensed Matter, Vol 23, 055501 (2011). ( Google Scholar Citation 70+)

8.  Electron optics with magnetic vector potential barriers in Graphene, Sankalpa Ghosh and Manish Sharma, Journal of Physics Condensed Matter, Vol 21, 292204 (2009). ( Fast Track Communication, Free to Read.) (Google Scholar Citation 150)

Awards/Honours

1. JSPS Post Doctoral Fellowship ( 2005).

2. DAE SRC Outstanding Investigator Award 2013-2014” by Department of Atomic Energy, Govt. of India. 

Projects (Completed /Ongoing )

1. Electron Transport in Graphene: Effect of electromagnetic potential barriers, impurities and electron-electron interaction (2010-2013). Supported by Science and Engineering research Board ( formerly SERC), DST, Govt. of India.

2. Electro-Optical Property of Magnetically Modulated Graphene- UGC-UKIERI Thematic Award ( July, 2014- December, 2016) – Supported by UGC, GOI (India) and UKIERI (UK).

3. Ultra Cold Atoms in Synthetic Gauge Field: Cavity Optomechanics and Ensuing Quantum Simulation: 2016-2022 ( BRNS, DAE, Govt. of India)

Outreach: I  co-ordinated a GIAN course where Prof. Shivaji L. Sondhi from Physics Department, Princeton University (USA), delivered seven two hour lectures from 26th August, 2017 to 1st September, 2017. The title of the course is “ An introduction to Topological Insulators and Superconductors.  Students from various parts of the country attended. For more details on the course see the GIAN website link.

Preprint URL: http://arxiv.org/find/cond-mat/1/au:+ghosh_sankalpa/0/1/0/all/0/1

Researcher id Profile: http://www.researcherid.com/rid/B-7470-2009.

                 Google Scholar : Google Scholar Profile

Current Ph. D. Students : Disha Arora(2018), Shahrukh Salim, (2015), Poornima Shakya (2015), Inderpreet Kaur (2014), Manisha Arorra (2013)

Alumni : Dr. Rashi Sachdeva ( Post Doctoral Fellow, Lund University, Sweden):

             Dr. Jasleen Lugani  ( Post Doctoral Fellow, University of Oxford, UK)

             Dr. Neetu Agrawal (Garg), Doulatram College, Delhi University

             Dr. Puja Mondal

Highlights:

1. Kaleidoscope in Physical Review A, June, 2012.  SEE THE IMAGE

2. Kaleidoscope in Physical Review A, January, 2012, SEE THE PAPER   , SEE THE IMAGE

3. Highlights in Journal of Physics, Condensed Matter (2011), SEE THE COLLECTION  , SEE THE PAPER

4.INSA   Proceedings , Golden Jubilee IIT Delhi, FOLLOW THE LINK

     5.  Our  work on solitonic cold atoms in a disordered potential has been reported in the europhysicsnews

 

 

 

There is not only Dirac Equation: But also Dirac Entertainment:

      Some interesting sites:

1.   Cold atomic gases (A useful site for BEC watchers)

2.   Graphene (To know more about graphene click here)

3.   Ultra cold atoms in optical cavity 

4.   Topological Insulators

 

 

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To download home page template (readme.doc file) click here.