The functionality of logic and memory elements in current electronics isbased on multi-stability, driven either by manipulating local concentrations ofelectrons in transistors, or by switching between equivalent states of amaterial with a degener- ate ground state in magnetic or ferroelectricmaterials. Another possibility is offered by phase transitions with switchingbetween metallic and insulating phases, but classical phase transitions arelimited in speed by slow nucleation, proliferation of domains and hysteresis.We can in principle avoid these problems by using quantum states for switching,but microscopic systems suffer from decoherence which prohibits their use ineveryday devices. Macroscopic quantum states, such as the superconductingground state have the advantage that on a fundamental level they do not sufferfrom decoherence plaguing microscopic systems. Here we demonstrate for thefirst time ultrafast non-thermal switching between different metastableelectronically ordered states by pulsed electrical charge injection. Themacroscopic nature of the many-body quantum states(1-4) - which are not part ofthe equilibrium phase diagram - gives rise to unprecedented stability andremarka- bly sharp switching thresholds. Fast sub-50 ps switching, largeassociated re- sistance changes, 2-terminal operation and demonstrable highfidelity of bi-stability control suggest new opportunities for the use ofmacroscopic quantum states in electronics, particularly for an ultrafastnon-volatile quantum charge-order resistive random access memory (QCOR-RAM).
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