Enhanced metrology using quantum-correlated matter*

The best clock in the world has no hands, no pendulum, no digital display. It is made of ultra-cold atoms trapped in a crystal of light.
To date, this clock is the most precise table-top instrument built by humankind; had it begun ticking when the Earth first formed billions of years ago, it would not have gained or lost a second. Even so, current atomic clocks still use collections of independent atoms, and are fundamentally limited in precision by these atoms' intrinsic quantum noise. Here, I will discuss a simple protocol to break through this limit by entangling fermionic atoms in an optical lattice clock. The basic idea is to use atomic interactions to prolong inter-particle spin coherence, transforming the dephasing effect of spin-orbit coupling into a collective entangling process that generates spin squeezing. I will show squeezing can be further enhanced by driving the clock, and how even with realistic experimental imperfections our scheme can generate ~12-15 dB of spin squeezing with 10²-10³ atoms. I will also discuss how a generalization of this protocol can be used to generate high dimensional cluster states useful for one quantum computing. In addition to advancing the achievable precision of atomic clocks, our protocol showcases a new paradigm of employing driven, non-equilibrium systems to overcome current limitations in quantum metrology and for the development of the foundations necessary for the construction of a universal quantum computer.