In 2019, he became a founding director of NTT PHI Labs in Silicon Valley, California, the United States.

Some of Yamamoto's key works from this era are proposals for how to physically realize photon-number squeezing,[17] QND measurement,[18] and a gate model quantum computer using single atoms and photons.

[13][14] Yamamoto was also active in the development of security theory and realization of quantum key distribution protocols.

One highlight was the co-first demonstration (with Ataç İmamoğlu's group at ETH) of entanglement between a spin in a quantum dot and a photon emitted by it.

In 1992, he received the Nishina Prize[5] and the Carl Zeiss Award[6] on his pioneering work on squeezed state generation in semiconductor lasers.

In 2011, he received the Okawa Prize [2] on his pioneering work on single photon generation from a quantum dot.