DRAM chips, the ones in your laptop storing bits using capacitors inside a chip, are pretty good in terms of speed. They have a switching time in the order of 2 nanoseconds, that it the time it takes a beam of light to cover 60cm. And, remember, light travels really fast!
Now imagine that same beam of light traveling for 0.3µm (0.3 millionth of a meter): that correspond to a time of a femtosecond and in that time a pulse of a laser can activate the a memory switch (from 0 to 1 or vs), with the switch itself taking a few picoseconds, that is the time it takes light to travel a mm.
This is what researchers at Berkeley and their colleagues at Riverside have managed to achieve. The problem with RAM (Random Access Memory) and their siblings, like DRAM (Dynamic RAM) is that they need to be continuously powered otherwise they lose the data. This, in turns, requires energy and drain the battery.
An alternative is to use magnetic memory, magnetism is persistent, not like an electron charge that goes away unless you keep it where it is. The downside is that magnetic memories are much slower than electric memories.
In a paper published on Science Advances the Berkeley ad Riverside researchers present a magnetic memory based on Gadolinium (Gd, atomic number 64, a rare earth metal) with a much faster switching rate. Furthermore they have managed to activate the switching (that is the writing of a bit) using a 1 femtosecond laser pulse by overlaying a layer of cobalt. The actual switching requires 7 picoseconds.
Bringing this type of memory to the market means decreasing the need for power in line with the growing need of processing on the move.