A5068699937- Cosmology and Gravitation Theories
- Quantum Mechanics and Applications
- Relativity and Gravitational Theory
- Cold Atom Physics and Bose-Einstein Condensates
- Pulsars and Gravitational Waves Research
- Atomic and Subatomic Physics Research
- Quantum Information and Cryptography
- Advanced Frequency and Time Standards
- Quantum Electrodynamics and Casimir Effect
- Black Holes and Theoretical Physics
- Biofield Effects and Biophysics
- Quantum, superfluid, helium dynamics
- Noncommutative and Quantum Gravity Theories
- Advanced Thermodynamics and Statistical Mechanics
- Geophysics and Gravity Measurements
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Mechanical and Optical Resonators
- Scientific Measurement and Uncertainty Evaluation
- Gamma-ray bursts and supernovae
- Radioactive Decay and Measurement Techniques
- Quantum and electron transport phenomena
- Experimental and Theoretical Physics Studies
- History and Developments in Astronomy
- Astrophysical Phenomena and Observations
Defence Institute of Advanced Technology
2024
Tata Institute of Fundamental Research
2014-2023
Indian Institute of Astrophysics
2000-2004
Tata Institute of Social Sciences
2004
École Normale Supérieure - PSL
1999-2002
Leibniz University Hannover
2001
Laboratoire Kastler Brossel
2001
École Normale Supérieure
2001
We have observed a Bose-Einstein condensate in dilute gas of 4He the (3)2S(1) metastable state. find critical temperature (4.7+/-0.5) microK and typical number atoms at threshold 8 x 10(6). The maximum our is about 5 10(5). An approximate value for scattering length = (16+/-8) nm measured. mean elastic collision rate then estimated to be 2 10(4) s(-1), indicating that we are deeply hydrodynamic regime. decay time s, which places an upper bound on constants two-body three-body inelastic collisions.
Initiatives by the IndIGO (Indian Initiative in Gravitational Wave Observations) Consortium during past three years have materialized into concrete plans and project opportunities for instrumentation research based on advanced interferometer detectors . With LIGO-India opportunity, this initiative has a taken promising path towards significant participation gravitational wave (GW) astronomy research, developing nurturing precision fabrication measurement technologies India. The proposed...
We report enhanced sub-Doppler cooling of the bosonic atoms $^{39}$K facilitated by formation dark states tuned for Raman resonance in $\Lambda-$configuration near D1 transition. Temperature about 12 $\mu$K is achieved two stage D2-D1 molasses and spans a very large parameter region where quantum interference persists robustly. also present results on radiation heating with sub-natural linewidth (0.07$\Gamma$) signature Fano like profile coherently driven 3-level atomic system. The Optical...
We discuss the implementation and characterization of source a slow, intense, collimated beam rubidium atoms. The cold atomic is produced by two-dimensional magneto-optical trapping in directions transverse to axis unbalanced Doppler cooling axial direction. vacuum design allows use relatively low laser power considerably simplified assembly. has high flux about $2\ifmmode\times\else\texttimes\fi{}{10}^{10}\phantom{\rule{0.3em}{0ex}}\mathrm{atoms}∕\mathrm{s}$ at total...
We report the sub-Doppler deep-cooled three-dimensional magneto-optical trap (3D MOT) of fermionic 40K and bosonic 39K isotopes potassium loaded by a very compact 2D+ MOT with novel optical design feature. The set-up is meant for studies on quantum dynamics few atoms in an dipole near well within degeneracy. loading rate atom numbers achieved simple are comparable to those previous set-ups more elaborate vacuum design. attained relatively low temperatures 34 30 µK after cooling process.
We report on a measurement of the van der Waals interaction between rubidium atoms in ground state and metallic surface, employing new method involving reflection laser-cooled from magnetic thin-film atom mirrors. made use fact that typical distance which reflect mirrors is order domain size thickness thin film. The modification reflectivity cold cobalt mirrors, with range 200 − 20 nm, due to competition attractive atom-surface repulsive enabled force 20–50 nm an uncertainty 15%. measured...
An experiment to observe parity nonconservation using the $|{5p}^{6}6s{〉}_{1/2}\ensuremath{\rightarrow}|{5p}^{6}5d{〉}_{3/2}$ transition in ${\mathrm{Ba}}^{+}$ has been proposed [N. Fortson, Phys. Rev. Lett., 70, 2383 (1993)]. We have carried out relativistic configuration-interaction calculations explore whether $|{5p}^{6}6s{〉}_{1/2}\ensuremath{\rightarrow}|{5p}^{6}5d{〉}_{5/2}$ and $|{6p}^{6}7s{〉}_{1/2}\ensuremath{\rightarrow}|{6p}^{6}6d{〉}_{5/2}$ transitions ${\mathrm{Ra}}^{+}$ respectively...
The equality of the charges electron and proton, charge neutrality neutron are great significance in fundamental theory particles. This suggests a deep symmetry between leptons quarks that is not yet revealed other experiments. electrical bulk matter direct result this characteristic charges, with important consequences for precise tests physical laws metrology. question interest also cosmology. In paper, we discuss experimental evidence its implications possibility improved
The LIGO-India project to build and operate an advanced LIGO (aLIGO) gravitational wave (GW) detector in India collaboration with LIGO-USA was initiated as Indian national mega-science 2011. relied on the advantage of a head start cost saving due ready availability most aLIGO interferometer components from LIGO-USA, approved by National Science Foundation. A suitable site selected provisional governmental approval for obtained 2016, immediately following first direct detection waves...
A laboratory experiment searching for intermediate-range forces coupling to $N\ensuremath{-}Z$ of nuclei has been performed. This yields the bound on strength any such force be less than 3.0 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}3}$ gravity per baryon, all ranges $\ensuremath{\lambda}>3$ m.
We present arguments that rule out the recent suggestion by Wang et al. their observations of anomalous gravity data during 1997 total solar eclipse in China could be evidence for shielding Sun Moon, or pointing to some new property gravitation. In fact, we are able use stretch obtained before and after constrain characteristic parameter lowest bound ever from a terrestrial experiment.
We discuss our experimental results on forced evaporative cooling of cold rubidium 87Rb atoms to quantum degeneracy in an Optical Dipole Trap. The are first trapped and cooled a magneto-optical trap (MOT) loaded from continuous beam [1]. More than 1010 the MOT then about 108 transferred Quasi-Electrostatic Trap (QUEST) formed by tightly focused CO2 laser (λ = 10.6μm) beams intersecting at their foci orthogonal configuration horizontal plane. Before loading into dipole trap, phase-space...
Abstract The present framework of dynamics and relativity is based on Albert Einstein’s special general theories relativity. However, the empty featureless space its time that are assumed in constructing these direct conflict with reality vast universe enormous quantity matter-energy gravity. Gravitational interaction affects spatio-temporal intervals general. Since all physical phenomena as well attempt to describe them operative this single real universe, really existing given, factual...
A Comment on the Letter by Claudia Eberlein, Phys. Rev. Lett. 76, 3842 (1996). The authors of offer a Reply.Received 20 May 1996DOI:https://doi.org/10.1103/PhysRevLett.77.4690©1996 American Physical Society
String theory, as well the string inspired brane-world models such Randall-Sundrum (RS) one, suggest a modification of Newton's law gravitation at small distance scales. Search for modifications standard gravity is an active field research in this context. It known that short range corrections to would violate Newton-Birkhoff theorem. Based on calculations RS-type non-Newtonian forces finite size spherical bodies, we propose torsion balance based experiment search effects violation theorem...
We analyze the results from an experiment being conducted at Physik-Institut, Universit\"at Z\"urich to measure gravitational constant, and obtain a tight constraint on Majorana shielding factor. The limit we is two orders of magnitude lower than positive obtained by in 1920s factor about 5 better Braginsky more modern laboratory experiment. expected future provide which another 10 our present estimate.
There have been many speculations that the equivalence principle might be violated in situations involving quantum systems a classical gravitational field. Also, several authors stated experiments contain signatures, specific to interaction, are fundamentally different from what could explored experiments. I critically assess these statements and prove validity of for general Further, argue there should not any expectation violation neutrino sector. end with some comments on basic...