Dr. Mandip Singh
Introduction
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.
Quantum Technology and Foundations
Quantum Technology
Quantum interference with reversible detection of photons
Quantum double-slit experiment with Einstein-Podolsky-Rosen entangled photons-reversible detection
A double slit interference experiment with a continuous variable Einstein-Podolsky-Rosen (EPR) entangled photon pairs. Photon-1 is detected on the screen before photon-2 passed through a beam splitter and double-slit. Quantum interference gradually appears when experiment is repeated with many entangled photons, provided photon-2 is detected by a stationary detector-2 whereas photon-1 was already detected on screen. No single photon interference, even if another screen is placed after the double-slit. This experiment has no classical analogue.
Published in Scientific Reports: 14, 20438 (2024). Link
Experimental diagram
A main diagram of the experiment is shown on the right.
Quantum Interference
Quantum interference (a) when photon-1 is detected on screen and photon-2 is detected by detector-2 placed behind the screen. The detection of photon-1 cannot influence photon-2 by any signal propagating with the speed of light. (b) No single photon interference if a screen is placed behind the double-slit.
Sub-tomographic imaging in higher dimensional space (6D)
Sub-tomographic imaging of a transparent object localised in phase space
Experiment on sub-tomographic imaging of a transparent pattern localised in phase space (3D subspace of 6D phase space) is published in Scientific Reports: 14, 2641, (2024).
Experimental diagram is shown on the left.
Sub-tomographs of a transparent pattern localised in 3D phase space (a subspace of 6D phase space)
Transparent pattern localised in phase space cannot be viewed by any lens or an eye. The notion of patterns localised in a phase space was introduced by an experiment in 2018, see: Phys. Rev. A. 98, 053828 (2018).
This paper is extension of this concept for transparent objects localised in phase space.
Quantum Ghost Imaging (Transparent phase pattern)
Quantum Ghost Imaging
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.
Theory and Experiment
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
Quantum ghost interference results from the EPR-entanglement component of hyper-entangled state.
Nonlocal action acts in the past
Spooky action acts in the past
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]
Direct Quantum Imaging
Previous Direct Imaging
Quantum imaging of a polarisation sensitive phase pattern with hyper-entangled photons is published in Scientific Reports.
Experiment
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.
Imaging
Polarisation sensitive phase pattern and its images produced by joint measurement of both photons with different polarisation measurement of noninteracting photon.
Hyper-entangled state of photons
Probability of coincidence detection
Hyper-entangled state of photons
Momentum nd polarisation hyperentanglement
Quantum image state
Probability of coincidence detection
Hyper-entangled state of photons
Quantum state of photons immediately after interaction with the polarisation sensitive phase pattern.
Probability of coincidence detection
Probability of coincidence detection
Probability of coincidence detection
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.
Double-double slit experiment
Publication.
Paper on quantum double-double-slit experiment with momentum entangled photons is published in Scientific Reports.
TOP 100 in physics
Scientific Reports paper "Quantum double-double-slit experiment with momentum entangled photons" is among the top 100 physics papers published in 2020.
Quantum Experiments with photons
Quantum double-double-slit experiment
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.
Schematic of the experiment
Two photon detection amplitude
Two photon detection amplitude
Quantum double double slit experiment.
Two photon detection amplitude
Two photon detection amplitude
Two photon detection amplitude
Probability amplitude of two-photon detection on the screens.
Quantum interference of momentum entangled and path entangled photons
Quantum interference of momentum entangled and path entangled photons
Quantum interference of momentum entangled and path entangled photons
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.
Quantum measurement of a path of a photon
Quantum interference of momentum entangled and path entangled photons
Quantum interference of momentum entangled and path entangled photons
Interference pattern is not formed if path of any one photon is detected. Path entanglement is collapsed.
Quantum diffraction of Photons
Photon Entanglement and Quantum Diffraction
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).
Quantum diffraction from a sharp edge
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.
Macroscopic quantum entanglement
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)
Macroscopic quantum system
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).
Phase space Imaging Experiment
3D Tomographic imaging of a phase space pattern
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
Concept of a 3D tomographic imaging of a pattern in phase space (a).
(d) velocity selective hole-burning and
(c) a spatial domain image.
Phase Space Tomographic Imaging
Schematic diagram of experiment. For details: Phys. Rev. A, 98, 053828 (2018).
Teaching Aspect
Addition to research
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.
phy-edu
This section highlights published work in physics education research.
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).
Nonlinearity of PN junction diode.
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.)
Frequency comb generation by a PN junction diode
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.