# Summaries - Office of Research & Innovation

Research Summaries

### Back States of Light for Quantum Sensing-(Theory)

Fiscal Year | 2020 |

Division | Graduate School of Engineering & Applied Science |

Department | Electrical & Computer Engineering |

Investigator(s) | Mimih, Jihane |

Sponsor | Department of Defense Space (DoD) |

Summary | This proposal addresses strategic objective Autonomous Distributed Cyber-Secure Networking and Communications (specifically enabling secure and timely communication) and technical areas 4.1 Discovery Research in the area as well as 4.2 Fundamental Limits where quantum science is pushing the limit of precision beyond conventional technology. GPS satellites send radio signals on a constant basis transmitting the location and time they left the satellite. Receivers on Earth calculate the time delay from each satellite and convert this information to spatial coordinates. Determining the location of a spacecraft also works in the same way: A person on the ground sends a signal to the spacecraft and waits for a return signal from the spacecraft. Since the speed of the signal is known, the distance to the spacecraft is easily calculated. Therefore, the more accurate the clock, the better the location of the spacecraft is determined. Additionally, high bandwidth communication requires highly accurate clocks. Current high-speed communication systems require a master clock, often originating from GPS in order to function. Compact and more accurate clocks would enable higher bandwidth communication even in the absence of GPS. The goal of this project is to find a method by which collective atomic ensembles combined with non-classical observables allows for the performance of atomic spectroscopy for determining the frequency standard of a clock with higher precision than is possible with the usual population spectroscopy. The precision of an atomic clock depends on several variables including the number of atoms being used. The higher the number of atoms used, the better the precision is. In a conventional atomic clock, the precision is inversely proportional to the square-root of the number of atoms. However, in an entangled atomic clock, the precision is inversely proportional to the number of atoms (not the square root). It is therefore ideal to use a large number of atoms to build an entangled clock that is stable. The goal of this project is to apply the theory of optical interferometry using photon-number parity measurements to spectroscopy with ensembles of two-level atoms, keeping in mind that the Ramsey spectroscopy (described later on) technique is mathematically equivalent to an optical Mach-Zehnder interferometer. We would also like to investigate various types of entangled atomic states that could yield atomic clocks of higher precision and stability than is possible with independent atoms e.g. atoms that are not entangled. We will also investigate ways to perform efficient measurement of nonclassical operators such as the atomic parity, including a search for a quantum non-demolition measurement scheme that determines the parity without finding the number of atoms in the excited state. This is a theoretical project complementing a parallel experimental project. |

Keywords | atom interferometry optical interferometry quantum sensing |

Publications | Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal |

Data | Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal |