Electricity Reads Out Diamond Spins express
Quantum computers demand reliable memory. In a diamond crystal — carbon — information is stored as the orientation of microscopic magnetic needles (spins) at special defects. Reading these arrows with light was inconvenient: optics are bulky for chips. The new method works like developing photographic film.
First, the laser “exposes” the spin: if the arrow points one way, the defect ejects an electron into a microscopic trap at the diamond’s edge; if the other way, it doesn’t. The charge can sit there for hours. Then, by applying voltage and shining light again, the traps are shaken — and the collected electrons create a current pulse. The magnitude of this photocurrent reveals the original spin direction. The method, called CCDMR (magnetic resonance with charge capture), is entirely electrical: no need to catch faint flashes. It can be easily placed on a crystal, creating quantum chips the size of a fingernail.
Original abstract
as written by the authors arXiv:2510.25619
Electrical detection methods for solid-state spins are attractive for quantum technologies, being readily chip-scalable and not subject to the small photon budgets of single emitters. However, realising electrical spin readout in wide-bandgap materials with similar fidelity and bandwidth to optical approaches remains challenging. Here, we introduce a photoelectrical spin readout scheme that detects spin information stored long-term as trapped electrical charges. Using nitrogen-vacancy (NV) centres in diamond as a model system, spin-dependent photoionisation generates charge carriers that are stored in long-lived trap states at a diamond-metal Schottky junction. On-demand illumination of the junction under electrical bias releases stored charge, yielding a photocurrent transient proportional to the amount of trapped charge and hence spin state. Spin readout after coherent control of single NVs is demonstrated using charge readout in a protocol we call charge-capture detected magnetic resonance (CCDMR), and we use charge-based imaging to identify charge carrier generation and trapping processes. Our results establish CCDMR as a new technique for solid-state spin qubit readout, combining attaractive features of electrical detection with the stability of long-lived charge traps in wide-bandgap materials.
Electron traps in diamond are so stable that the charge stored in them can last for years — far longer than most laboratory instruments operate.
The idea of storing information in crystals is familiar from Superman: his Fortress of Solitude used crystals as a database. Diamond quantum chips are almost the same thing, only in reality.