There is a fourth now https://twitter.com/PhysRevLett/status/1354866900036153352 and a write up in Physics (The more casual write ups at APS about major topics): https://physics.aps.org/articles/v14/15

The actual article links:

[1]- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...

[2] - https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...

[3] - https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...

[4] - https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...