Editing John M. Martinis (section)

== The Discovery — Quantum Phenomena in Circuits ==

=== The Challenge ===
For decades, physicists sought to connect quantum mechanics — the physics of atoms and subatomic particles — with macroscopic systems large enough to build machines.

Most believed that '''quantum behavior''' couldn’t survive in circuits visible to the naked eye because of noise and thermal fluctuations.

=== The Breakthrough ===
In the 1980s and 1990s, Martinis and his colleagues conducted landmark experiments demonstrating '''macroscopic quantum tunneling''' — a phenomenon where electrical current could “jump” through energy barriers, just like quantum particles.

By designing ultra-sensitive '''superconducting circuits''', cooled near absolute zero, Martinis showed that electrons could behave collectively as a single quantum entity — even in electrical devices containing billions of atoms. ''(source: Nature)''

This experimental confirmation of quantum tunneling in circuits proved that '''quantum mechanics applies not only to atoms but to engineered systems''' — a discovery that opened the path to '''quantum computing'''.
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