December-2017 Seminar

Date : 27-12-2017
Time : 16:00:00
Speaker : Ms. Shubhra Sharma
Area : Geosciences Division
Venue : Ground Floor Lecture Hall

Abstract

Projections based on the climate change scenario predict increased frequency and/or increased magnitude of floods in the Himalayan region due to more intense and frequent coupling between the Indian Summer Monsoon (ISM) and the mid-latitude westerlies. In view of this, studies pertaining to the geological evidence of extreme hydrological events (paleo-floods) become important as these extend beyond the instrumental records and ensure better understanding of the river response to the climate variability. The Satluj River in the north-western Himalaya is frequented by devastating floods in the recent past thus suggesting its sensitivity towards extreme hydrological events. We studied the sedimentary records of palaeofloods in the middle Satluj which has preserved around 27 flood events of increasing magnitude. The geochemical fingerprinting (based on CIA) indicates that the floods were generated in the Higher Himalayan Crystalline with contribution from the trans-Himalaya. Optical chronology allowed us to constrain the floods into four major clusters (viz. 13-11 ka, 8-5 ka, ~4 ka and <2 ka). Climatically, these clusters represent the transitional climatic conditions during the Holocene and are contrary to the earlier studies where intensified Indian Summer Monsoon (ISM) was implicated for the floods in the Himalaya. In this presentation, I would be giving a broad overview of the existing studies on paleo floods in the Indian Himalaya, with an emphasis on the causes of Holocene floods in the middle Satluj valley and their implications towards understanding the synoptic scale coupling (Arctic and North Atlantic Oscillation).

Title : Emergent quantum heat pump in a driven quantum gas

Date : 14-12-2017
Time : 16:00:00
Speaker : Dr. Arko Roy (Max Planck Institute for the Physics of Complex Systems, Dresden, Germany)
Area : Theoretical Physics
Venue : Room No: 469

Abstract

We propose a novel scheme for quantum heat pumps powered by rapid time-periodic driving. We focus our investigation on a system consisting of two coupled driven quantum dots in contact with fermionic reservoirs at different temperatures. Such a configuration can be realized in a quantum-gas microscope. Theoretically we characterize the device by describing the coupling to the reservoirs using the Floquet-Born-Markov approximation.

Date : 12-12-2017
Time : 16:00:00
Speaker : Mr. Abdur Rahman
Junior Research Fellow
Area : Geosciences Division
Venue : Ground Floor Lecture Hall

Abstract

Lake sediments form an important archive to study paleoclimate and paleobiological condition in the continental interior. Stable isotopic composition of carbon and nitrogen in organic matter of the lake sediment provide an important insight into the paleovegetation and nutrient conditions. However, reconstruction of paleotemperature and paleoprecipitation in high altitude environment lacking in situ calcite formation remains challenging. Oxygen isotopes measurement of diatoms using laser fluorination technique in lake sediments has the potential to provide a robust proxy for the same. During this talk, I will explain the methodology, its importance and analytical challenges regarding this technique along with preliminary results of carbon isotopic composition in organic matter from a sediment core in a Himalayan lake.

Date : 06-12-2017
Time : 16:00:00
Speaker : Prof. Padmakar Parihar
Area : Astronomy & Astrophysics Division
Venue : Seminar Room # 113/114 (Thaltej Campus)

Abstract

Recently install 3.6m DOT telescope and forthcoming TMT would not be enough to cater the need of growing Indian astronomical community. Access to 10­ - 12m size optical­-NIR telescope equipped with state of the art back­-end instruments can bridge the gap between DOT and TMT. A telescope of this size is only possible when primary mirror is made of smaller mirror segments. The participation into TMT project has given us an opportunity to adopt some the key technologies linked with segmented mirror telescope(SMT) and make use of resources being developed for this mega project within India. In my talk I will present the possible sites for the proposed telescope, preliminary opto­-mechanical design and some R&D effort happening in IIA to explore SMT technology by developing a prototype segmented mirror telescope.

Title : Novel quantum phases of ultracold bosonic atoms in optical lattices

Date : 05-12-2017
Time : 16:00:00
Speaker : Dr. Kuldeep Suthar
Post Doctorate Fellow
Area : Theoretical Physics
Venue : Room no:469

Abstract

Ultracold atoms provide a novel route to exotic quantum phases of matter. In particular, phases which display coexistence of different types of order. For example, can a solid be superfluid? The quest for this state has been one of the grand challenges in condensed matter physics and dates back to the first prediction of supersolid in $^{4}$He. Supersolidity combines superfluid properties with long-range spatial periodicity of solids. Recent experiments have reported the observation of characteristic signatures of this phase in ultracold quantum matter. To study various quantum phases and their transitions we employ Gutzwiller mean-field approximation in extended Bose-Hubbard model. In this talk, we shall discuss the phase diagram, the effect of synthetic magnetic field on phases and stability of supersolid phase in the presence of long-range interactions.