# Hello there!

# Welcome to my page

I am Sayan, an undergrad @ IISER Kolkata

## A little about me

My name is Sayan Ghosh and I am a Bachelor of Science student

I love to create physical problems and solve them and search for easier solutions of known problems. I am also passionate about natural science, especially how it all works. I also love to study "paradoxes". Currently I am studying and working with light, which I think to be the best of all creation.

In the spare time I like to watch movies and play video games. I am also a numismatist.

# My studies

I am a BS-MS student at Indian Institute of Science Education and Research and I am looking forward to pursue a career of scientist.I am interested in almost everything in the field of physical sciences and specially in optics, quantum physics and condensed matter physics.

See the section below for more about my research interests

*"God not only plays dice, but also sometimes throws them where they cannot be seen"*

## Orbital angular momentum in light beams

In 1992 Allen et al. predicted theoretically that light beams with helical phase can carry orbital angular momentum. And later it was experimentally verified. OAM beams have been very useful in many aspects, especially in quantum optics, quantum computing and studying light-matter interaction. And it is quite useful as it provides large (theoretically infinite) degrees of freedom, while spin angular momentum, which is related to polarization, provides only two. By now techniques of generating beams with any value of orbital angular momentum, even with fractional angular momentum is well known.

### OAM in LG modes

Lagueree Gaussian modes of paraxial waves carry orbital angular momentum. These are perhaps the simplest example of light carrying orbital angular momentum.

### Optical vortices

Nonzero OAM modes (integer as well as fractional) and higher order zero OAM modes have optical vortex structures. Fractional OAM modes have rather irregular structure. Optical vortices have various applications. Vortex beams have large degrees of freedom. They are also used in equipments like optical tweezers. And it is also useful to study light-matter interaction observing vortex transformation or Hall effect.

### Perfect vortices

Perfect vortex beams were created to confine vortex beams with large topological charge in a small area. The size of the singular region is independent of the OAM of the beam.

# Weak measurement

Quantum measurements, the so called strong measurements are projective and destroys interference in quantum states. On the other hand, one can design an experiment where we very weakly couple our system with the measuring device to preserve superposition. This weak measurement occurs in between two other projective measurement and the whole scheme, introduced by Aharonov, Albert and Vaidman in a groundbreaking work is called weak measurement. If the strong measurements are projective in almost orthogonal directions, the effect of interaction (which one can think of as pointer reading) called the weak value is amplified in orders of magnitude.

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