Quantum Science with Ultracold Molecules (QSUM): Vision and Objectives

Our vision is to achieve full quantum control of cold and ultracold molecules in order to advance the science of complex quantum systems and underpin new quantum technologies.

Key challenges:

(1) Advanced Molecular Sources: The application of molecular sources in the solid state, in traps and in lattices, to developing quantum science.
(2) Interfaces: Controlled coupling of molecules in the solid state to photonic chips.
(3) Chips: Controlled coupling of gas-phase molecules in microtraps to waveguides on a chip.
(4) Tweezers: Controlling molecule-molecule interactions and engineering entanglement.
(5) Lattices: Preparing and detecting the quantum states of molecules in optical lattices.
(6) Microscope: Detecting and addressing individual molecules in a 2D quantum array and performing prototype quantum simulations.

Objectives:

(1) Advanced Molecular Sources:

  1. Develop new sources of ultracold CsYb and KCs molecules using association techniques.
  2. Cool CaF molecules to sub-Doppler temperatures.
  3. Identify the best sympathetic cooling protocols to cool CaF to high phase-space density.
  4. Develop methods to align the dipoles of organic dye molecules on functional substrates.

(2) Interfaces:

  1. Couple single dye molecules in a crystalline matrix to nanophotonic cavities and waveguides.
  2. Develop a quantum gate based on the differential phase shift of photons passing a molecule.
  3. Develop an integrated quantum memory based on long-lived states of these molecules.

(3) Chips:

  1. Develop micro-structured electric traps on a chip.
  2. Load molecules into these chip traps.
  3. Integrate waveguides that deliver microwave photons to prepare the quantum state of molecules.

(4) Tweezers:

  1. Demonstrate single-atom and single-molecule loading of an optical tweezer.
  2. Make single ground-state molecules in an optical tweezer by association of atoms.
  3. Cool molecules to the motional ground-state.
  4. Make a linear array of molecules and entangle them via the dipole-dipole interaction.

(5) Lattices:

  1. Produce ultracold 1Σ and 2Σ molecules in optical lattices.
  2. Probe dipole-dipole interactions and quantum magnetism in lattices by microwave spectroscopy.
  3. Investigate and understand effective spin-spin interactions in the lattice.
  4. Understand the role of topological states in the many-body quantum system and explore their applications in quantum information processing.

(6) Microscope:

  1. Build a two-species quantum-gas microscope.
  2. Demonstrate site-resolved detection of ultracold molecules.
  3. Exploit controlled dipole-dipole interactions to investigate novel many-body quantum phases in a 2D square lattice.

Underpinning all of these are the following broader objectives which span multiple projects:

  1. Understand how to control molecules using combinations of electric, magnetic and microwave fields.
  2. Understand how the complexity of real molecules has impact on idealised models of few-body and many-body systems of interacting dipoles.
  3. Develop experimental methods to quantify entanglement between molecules.
  4. Identify and assess the most promising applications of molecules to quantum simulation, and quantum enhanced measurement.