This award supports research and education in theoretical quantum physics focusing on the study of the quantum properties of electrical circuits operating at microwave frequencies and at temperatures close to absolute zero. Rather than dealing with lasers, photons at optical frequencies, and individual real atoms, the PI studies microwave photons and artificial atoms constructed from superconducting circuit elements. Because the artificial atoms (called qubits) are enormously larger than individual real atoms, their interaction with photons can be significantly larger than the interaction between ordinary light and atoms. This permits testing the implications of quantum mechanics in completely new regimes, as well as creating exotic quantum states of qubits and photons, which can be used as the basis for building a quantum computer and for secure quantum communication based on the transmission of photons. This project will also develop and study methods for storing and faithfully transmitting quantum information using photons, even if photons are lost during transmission over long distances or during storage over long periods of time in a quantum memory.
Because of recent enormous experimental progress, it is now possible to detect individual photons with unprecedented sensitivity. This project will take advantage of these advances to propose methods that will dramatically speed up the search for a certain class of dark matter particles known as axions, which will forge important new connections between the fields of condensed matter physics and cosmology.
Finally, the PI will continue his collaboration with experimental colleagues to study quantum optomechanics, in which the feeble radiation pressure of light is harnessed to control the motion of mechanical objects, and make position measurements with unprecedented accuracy. The recent discovery of gravitational waves at LIGO is an example of one of the practical applications for this type of research.
The project will achieve broader impacts by its interdisciplinary nature and the close collaboration with experiment. The PI is fostering communication among the condensed matter, atomic physics, quantum optics and electrical engineering communities. As part of the project a postdoctoral fellow will be trained in cutting-edge theoretical methods. The PI is also responsible for an annual lecture for approximately 200 high-school students from across New England as part of the Yale Physics Olympics, focused on explaining ideas from quantum mechanics and quantum information processing.
This award supports research and education in theoretical quantum physics focusing on the application of ideas from quantum optics and cavity quantum electrodynamics to circuit QED. The project involves four main areas of research:
1) Strong-coupling of a superconducting qubit to a multi-mode cavity: This project will study nonlinear quantum optics in the limit where the free spectral range of a one-meter-long resonator is small enough to be comparable to the vacuum Rabi coupling of a qubit to that resonator. Thus, many modes are jointly coupled to the qubit and hence to each other.
2) Efficient Detection of Microwave Photons for Axion Searches and Remote Entanglement: This project will propose and develop novel methods to use tools from circuit QED to detect cosmological axion dark-matter particles. Two different schemes will be analyzed, the first using two-mode squeezers to amplify the axion signal without amplifying the vacuum noise, and the second using recently developed capabilities for quantum non-demolition detection of microwave photons to create a "photomultiplier" for microwave photons. The PI will develop an optimal Bayesian filter to minimize the dark count rate of the detector and hence dramatically increase the signal-to-noise ratio for the detection of axions relative to current methods. The same ideas can be applied to the remote entanglement of qubits in independent cavities, which will have important application in the development of quantum computers.
3) Error Correctable Photonic Codes for Quantum Memories and Communication: This project sits within fundamental quantum information theory. It will take advantage of new experimental capabilities, which allow essentially universal control and measurement of complex superpositions of Fock states of small numbers of microwave photons and superconducting qubits, and have no analog in ordinary optics. The PI will develop approximate continuous quantum error correction protocols for bosonic modes. These will have applications to using microwave resonators as quantum memories, to quantum communication using microwave photons, and to faithful conversion of quantum information stored in microwave photons up to optical frequencies where it can be transmitted large distances over fiber networks.
4) Optomechanics: This is a fundamental quantum optics collaboration with experimental colleagues at Yale. The PI is particularly interested in the development of a fully quantum theory of non-adiabatic evolution near so-called "exceptional points" in the parameter space.
The project will achieve broader impacts by its interdisciplinary nature and the close collaboration with experiment. The PI is fostering communication among the condensed matter, atomic physics, quantum optics and electrical engineering communities. As part of the project a postdoctoral fellow will be trained in cutting-edge theoretical methods. The PI is also responsible for an annual lecture for approximately 200 high-school students from across New England as part of the Yale Physics Olympics, focused on explaining ideas from quantum mechanics and quantum information processing.
