Research

Quantum Sensors

Currently, most force sensors such as Michelson-Morley interferometers or atomic force microscopes, and magnetic field sensors (involving many types of NMR systems) are limited by thermal or material impurity noise sources. By better control of the system, and by engineering the environment, we are approaching the limits of sensing small forces and fields set by quantum mechanics.

However, dealing with various types of quantum effects requires more subtle techniques due to the inherent nature of the physics involved. In order to control quantum noise, we need to use quantum mechanics as a resource. For example, correlations between observables can lead to noise suppression, as in the case of squeezing. We can also couple different quantum systems to coherently cancel quantum noise or create entangled states.

Along with understanding and using quantum noise to enhance the efficiency of sensors, we also work towards identifying new quantum platforms to be used as sensitive detectors.

Below is a list of some of our recent publications in this area:

  • S. Singh, L.A. DeLorenzo, I. Pikovski, and K.C. Schwab, Detecting continuous gravitational waves with superfluid 4He, arXiv:1606.04980 [gr-qc] (2016). [link] Accepted for publication in NJP.
  • F. Bariani, H Seok, S. Singh, M Vengalattore, P Meystre, Atom-based coherent quantum-noise cancellation in optomechanics, Phys. Rev. A 92, 043817 (2015). (Editors’ Suggestion) [link]
  • S. Singh, Y. Chu, M. Lukin, and S. F. Yelin, Coherent Population Trapping, Nuclear Spin Cooling, and L ́evy Flights in Solid-State Atom-Like Systems, Adv. Atom. Mol. Opt. Phys. 64, 273 (2015). [link]
  • S. K. Steinke, S. Singh, P. Meystre, K. C. Schwab, and M. Vengalattore. Quantum back-action in spinor condensate magnetometry, Phys. Rev. A 88, 063809 (2013). [link]

Quantum Machines

While manifestations of the quantum nature of radiation and matter have been observed and understood for decades, the direct observation and control of quantum states of the light and matter is a more recent development. Quantum Hamiltonians are now routinely realized on disparate platforms including atoms, superconducting qubits, quantum dots, and deep defect centers in solids. As more dissimilar platforms get experimentally controlled at the single quantum level, an apparent theoretical opportunity is to recognize ways of using these devices as machines.

The challenge in controlling quantum effects in most devices arises from their large decoherence rates. Inherent quantum fluctuations, and the very nature of quantum measurements add to the complexity of building quantum machines. However, quantum mechanics can also be used as a resource, improving the performance of these machines.

Below is a list of some of our recent publications in this area:

  • Q. Song, S. Singh, K. Zhang, W. Zhang, and P. Meystre, One qubit and one photon: The simplest polaritonic heat engine, Phys. Rev. A 94, 063852 (2016). [link]
  • Roshan Sharma and Frederick W. Strauch, “Quantum state synthesis of superconducting resonators“, Phys. Rev. A 93, 012342 (2016) [link]
  • Kurt Jacobs, Hendra I. Nurdin, Frederick W. Strauch, and Matthew James, “Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: Analytical results in the regime of ground-state cooling“, Phys. Rev. A 91, 043812 (2015) [link]
  • F. Bariani, S. Singh, L.F. Buchmann, M. Vengalattore, P. Meystre, Hybrid optomechanical cooling by atomic Λ systems, Phys. Rev. A 90, 033838 (2014). [link]

Quantum Computing and Quantum Information

..under construction..