As advanced as technology may become, sometimes it is worth looking back at how things were done before. This is exactly what researchers at NIST have done as they have brought back a kind of mechanical memory for use in quantum computers. An earlier form of this technology was also used in the institutes SEAC computer in the 1950s.
The mechanical memory operates like a drum, which vibrates in response to a signal. The researchers are bringing it back by tuning it to work with microwaves that store quantum information in their amplitude and phase. When tested the researchers were able to achieve a 65% information retrieval rate. While that is quite low for electronic memory, given the still experimental nature of quantum memory, it is actually quite competitive.
The researchers envision this memory being built into chips with superconducting qubit thanks to its size and fabrication method being compatible with the other technology. Also the lifetime of the stored information is roughly the same as that in superconducting circuits.