Catalytic Coherence

Understand

Due to conservation of energy we cannot directly turn a quantum system with a definite energy into a superposition of different energies.

• However, if we have access to an additional resource in terms of a system with a high degree of coherence, as for standard models of laser light, we can overcome this limitation.
• The question is to what extent coherence gets degraded when utilized.
• Here it is shown that coherence can be turned into a catalyst, meaning that we can use it repeatedly without ever diminishing its power to enable coherent operations.