Collective Quantum Memory Activated by a Driven Central Spin

Abstract

Coupling a qubit coherently to an ensemble is the basis for collective quantum memories. A single driven electron in a quantum dot can deterministically excite low-energy collective modes of a nuclear spin ensemble in the presence of lattice strain. We propose to gate a quantum state transfer between this central electron and these low-energy excitations—spin waves—in the presence of a strong magnetic field, where the nuclear coherence time is long. We develop a microscopic theory capable of calculating the exact time evolution of the strained electron-nuclear system. With this, we evaluate the operation of quantum state storage and show that fidelities up to 90% can be reached with a modest nuclear polarization of only 50%. These findings demonstrate that strain-enabled nuclear spin waves are a highly suitable candidate for quantum memory.We thank E. Chekhovich for helpful discussions. This work was supported by the ERC PHOENICS grant (617985), the EPSRC Quantum Technology Hub NQIT (EP/M013243/1), and the Royal Society (RGF/EA/181068). D. A. G. acknowledges support from St. John’s College Title A Fellowship. E. V. D. and J. M. acknowledge funding from the Danish Council for Independent Research (Grant No. DFF-4181-00416). C. L. G. acknowledges support from a Royal Society Dorothy Hodgkin Fellowship

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