500GHz Transistor

John Cressler's research group at Georgia Tech and IBM have created an SiGe chip that runs at 500GHz. They achieved this by cooling the device to 4.5K. But it wasn't a slow technology to start with, having a room-temperature switching speed of 350GHz.

If I did this right, Landauer's Limit says that at 350GHz of bit destructions @300K, each transistor would generate 1.5nanowatts. So, a billion-transistor chip would have a physical, fundamental limit of at least 1.5 watts, unless reversible computing is used. Still, we're clearly orders of magnitude from that limit... (I may have dropped a small constant there, but I think I'm within a factor of two.)