# Nicole Yunger Halpern publishes in Nature Physics on the intersection of quantum computation and nonequilibrium physi

Nicole Yunger Halpern (IPST/NIST//QuICS) co-authored an article titled “Linear growth of quantum circuit complexity” published in Nature Physics, March 28, 2022. The article was profiled in Nature Physics, March 28 and Physics World on May 3,

The team proved a prominent conjecture by Brown and Susskind about how random quantum circuits' complexity increases. Consider constructing a unitary from Haar-random two-qubit quantum gates. Implementing the unitary exactly requires a circuit of some minimal number of gates - the unitary's exact circuit complexity. They proved that this complexity grows linearly with the number of random gates, with unit probability, until saturating after exponentially many random gates.

On March 31, Younger Halpern published an article in Quanta Magazine titled “Beyond the Second Law” citing work by Chris Jarzynski. “...Properties of a system far from equilibrium participate in an equality with equilibrium properties. My colleague Chris Jarzynski at the University of Maryland discovered this in 1997. (He’s so modest, he calls the equality the nonequilibrium fluctuation relation, while the rest of us call it Jarzynski’s equality.)”