Quantum coherence and interference in ultracold reactions

Coherent control over chemical reactions has been a long-standing goal in chemistry. However, coherence and entanglement are fragile to environmental decoherence. Nuclear spins provide a well-controlled and isolated degree of freedom within molecules, prompting us to probe their coherence in the context of chemical reactions. Herein, we study the preservation of coherence of nuclear spins in the 2KRb $\rightarrow$ K$_2$ + Rb$_2$ at 500 nK. By preparing a superposition of nuclear spin states within the initial KRb molecule, we observe specific K$_2$ and Rb$_2$ product channels destructively interfere through the reaction, a signature of coherence. This observed phase coherence prompts future experiments engineered around utilizing imparting phases as a tool to coherently control the product state distribution.