**Quantum Physics: **

Quantum Foundations

Quantum Computation

Quantum Information Processing

Photon & Ultracold Atoms

Quantum Optics

** Profession**: Physicist (Associate Professor of Physics) and independent research group leader at Indian Institute of Science Education and Research (IISER) Mohali, India.

**Research Interests**: Quantum Physics: Foundations of quantum physics, Quantum entanglement, Quantum information processing & quantum imaging, Quantum computer technology, Bose Einstein condensation (BEC-experiments) and general physics. (Experimental and Theory)

**Research funded by the Department of Science and Technology (DST). **

Principle investigator and lead scientist of an independent research project,

Project: Quantum Enabled Science and Technology, Theme- Quantum Information Technologies with Photonic Devices.

Project successfully completed on 31 March 2024.

**Education:**

- PhD in Experimental Physics, Swinburne University of Technology, Melbourne, Australia. 2008. Thesis advisor: Prof. Peter Hannaford.
- Master of Technology (Interdisciplinary M. Tech degree course) in Opto-electronics and optical communication, Indian Institute of Technology, Delhi (IIT Delhi).
- Master of Science in Physics.

**Post. Doc:** Institute for Quantum Optics and Quantum Information (IQOQI-University of Vienna, Wein, Austria. (Europe).

- From the group of Prof. Anton Zeilinger (Nobel Laureate 2022).

Dr. Mandip Singh is doing research in multidisciplinary experimental quantum physics and theoretical foundations of quantum physics. He is working on quantum entangled photons based quantum information processing and quantum technology experiments. In parallel, he is doing research on quantum foundations. His multidisciplinary research approach is object oriented which is essential to the development of quantum technologies such as for the development of a quantum computer.

He is leading a research group at IISER Mohali. He has supervised and supervising PhD students on different projects on quantum entanglement experiments, quantum optics, higher dimensional imaging and quantum information processing with photons.

Previous experiments: Dr. Mandip Singh has established photon entanglement and quantum optics experiments for research on quantum information processing and quantum foundations at IISER Mohali in 2015. In addition, Dr. Mandip Singh has started and developed Bose Einstein condensation experiments at IISER Mohali during 2012 to 2015. This is the first experiment, which he has developed completely independently at this place from the absolute scratch without a PhD student or a postdoc. This BEC experimental setup involves designing of vacuum system for the realization of ultra high vacuum (UHV), realization of a laser control system for BEC laser cooling and its imaging, making of an atom chip, control electronics, making of LabView programs (control and BEC imaging analysis interface) and execution of the experiments. A photograph of the setup is shown on top with an atom chip.

A subtomographic imaging experiment to image a transparent pattern localised in phase space.

Ref: Sci. Rep. 14: 2641 (2024). Link

Photon-2 is imaged on the camera which has never interacted with the pattern and a quantum ghost image is formed in coincidence measurements of momentum-polarization of photon-1 and polarization-position of photon2.

Quantum ghost imaging of a transparent polarisation sensitive phase pattern- published in Scientific Reports.

This experiment is different than conventional quantum ghost imaging experiments. A transparent polarization dependent phase pattern is quantum imaged with EPR (Einstein-Podolsky-Rosen)-polarization hyper-entangled photons. A millimeter size pattern is imaged from a distance of about 19 meters in free space. A complete analysis is presented in this paper. Hyper-entanglement is absolutely neccessary.

Quantum ghost interference results from the EPR-entanglement component of hyper-entangled state.

Spooky action at a distance was coined by A. Einstein. This is a phenomenon by which an action at a distance can happen immediately by making a measurement on a distant particle of a quantum entangled particle pair.

By combining the principle of simultaneity of relativity and Bell's theorem, it is shown that if a spooky action acts in the present then it also influences the past in the same way. This result is shown in this paper

Spooky action at a distance also acts in the past. by Mandip Singh. arXiv: 2109.04151v2 [quant-ph]

Quantum imaging of a polarisation sensitive phase pattern with hyper-entangled photons is published in Scientific Reports.

Hyper entangled photons produced by BBO source are separated part and measured jointly in momentum and polarisation basis where only one photon interacts with the pattern. Hyper-entangled photons are momentum entangled and polarisation entangled separately. Polarisation sensitive pattern changes the quantum polarisation entangled state of photons only without absorption.

Polarisation sensitive phase pattern and its images produced by joint measurement of both photons with different polarisation measurement of noninteracting photon.

Momentum nd polarisation hyperentanglement

Quantum state of photons immediately after interaction with the polarisation sensitive phase pattern.

Probability of coincidence detection of photons when noninteracting photon is measured in a selected momentum and a polarisation state. Interacting photon position and polarisation is measured in a selected basis.

Paper on quantum double-double-slit experiment with momentum entangled photons is published in Scientific Reports.

Scientific Reports paper "Quantum double-double-slit experiment with momentum entangled photons" is among the top 100 physics papers published in 2020.

Quantum mechanics is based on counter-intuitive principles.

We have performed a detailed experiment on a quantum double-double-slit experiment consisting of two double-slits with momentum entangled photons. Quantum entanglement of photons is such that each photon can reveal the which slit path information of the other photon. However, experiment can be performed in such a way that the which slit path information cannot be recovered after detection of particles. In the later case photons show two-photon interference. A detailed experiment with sound theoretical analysis is presented in the paper.

Quantum double double slit experiment.

Probability amplitude of two-photon detection on the screens.

Single photon and two photon interference patterns in the quantum double-double-slit experiment when both photons are path entangled via the slits. Effective wavelength of photons is half.

Interference pattern is not formed if path of any one photon is detected. Path entanglement is collapsed.

Quantum entangled state cannot be written in a product form even if individual particles are separated.

In my lab at IISER Mohali, we have performed a new experiment to produce position-momentum entangled states of two photons. Quantum diffraction of position-momentum entangled photons from a sharp edge is experimentally observed. Experimental results are understood based on a continuous variable entanglement quantum model. This is the first experiment on quantum diffraction of quantum entangled photons from a sharp edge that involves continuous variable entanglement.

For details: Phys. Letts. A. 383, 125889, (2019).

Experimental diffraction pattern of position-momentum entangled photons (dotted). Solid line plot represents a plot generated by a continuous variable entanglement model. Quantum diffraction pattern cannot be visualised by individual photon detectors, neither by a human nor by animal eyes. Such a pattern can be observed in joint detection of both photons known as correlated measurements. One of the interesting aspects of quantum mechanics is that it can recover patterns from completely random outcomes. It is often possible to find out complimentary patterns which cannot be measured simultaneously.

This section is about my research on quantum magnetic field and its interaction with atoms.

Fields are quantum of nature and particles are energy excitation of a field. Quantum superposition of magnetic field can produce interesting quantum states of interacting BEC. One such quantum state is a macroscopic entanglement of path of a single Bose Einstein condensate. Quantum magnetic field can produce macroscopic quantum entanglement of BEC.

Further details: Mandip Singh, Phys. Rev. A. 95, 043620, (2017)

This research work is about generalization of a flux qubit.

Displacement of a close loop superconducting cantilever is coupled with the net magnetic flux linked to the loop. Its ground state has features of quantum entanglement. Coupling constant of cantilever displacement with the net magnetic flux depends on the external magnetic field. In this way, coupling can be controlled externally and quantum entanglement of macroscopic quantum variables can be produced. Mandip Singh, Phys. Letts A. 370, 2001-2006 (2015).

Mandip Singh introduced the conceptual idea of localization and imaging of patterns in a phase space. He performed experiments on this concept in 2017 and published it in 2018.

Patterns in phase space cannot be imaged with a lens and eye. This research is about imaging of a pattern localised in a phase space. A part of the experiment on a three-dimensional tomographic imaging of a phase space pattern is shown on left.

For details: Phys. Rev. A, 98, 053828 (2018).

Concept of a 3D tomographic imaging of a pattern in phase space (a).

(d) velocity selective hole-burning and

(c) a spatial domain image.

Schematic diagram of experiment. For details: __Phys. Rev. A, 98, 053828 (2018).__

Dr. Mandip Singh has taught different types of courses of general physics and advance level physics at IISER Mohali since 2012. He is a recipient of best teacher award of the year in 2016. More specifically, he has introduced and developed pre PhD courses on Quantum Principles and Quantum Optics, Nonlinear Optics and Laser Fundamentals and Applications.

He has given public lectures on quantum physics at different colleges and universities and delivered lecture series in conference workshops.

In addition to research, Dr. Mandip Singh has developed new methods, which can be useful in teaching curriculum. Two experiments of this project are published.

Paper published in American Journal of Physics was featured on the cover page of the journal, June 2018 issue.

Experiment of diffraction of laser beam from moving sharp edges is featured on the cover page of American Journal of Physics, June 2018.

Diffraction effects in mechanically chopped laser pulses. S. Gambhir and M. Singh, 86, 406, (2018).

This experiment shows all orders of nonlinearity of a PN junction diode. Harmonic generation, sum difference frequency generation, frequency comb generation up to the twentieth harmonic by a single PN junction. (IAPT Physics Education,Vol 32, 2, Apr-Jun 2018, ISSN: 0970-5953.)

A frequency comb generated by using nonlinearity of a PN junction diode. Highest frequency is the twentieth harmonic of the driving voltage. Published in IAPT physics education, Apr-Jun 2018.

Elective courses

- Quantum Computation and Quantum Information (elective course)
- Quantum Principles and Quantum Optics. (elective course: designed by Mandip)
- Nonlinear Optics. (elective course: designed by Mandip)
- Laser Fundamentals and Applications. (elective course: designed by Mandip)

Undergraduate and Pre PhD courses:

- Optics and Advanced Spectroscopy (third year undergraduate laboratory course)
- Hands on Electronics (second year undergraduate laboratory course)
- Review of Quantum Mechanics (pre Ph.D course)
- Review of Electrodynamics (pre Ph.D course)
- Electricity and Magnetism (second year undergraduate course)
- Electrodynamics (third year undergraduate course)
- Waves and Oscillations (second year undergraduate course)

- Energy and Motion
- Digital Signal Processing

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