Quantum materials and qubit synthesis with intense ion beams*

We present results on laser-ion doping of diamond samples where we observe a superconducting phase at transition temperatures in the 0.5 K range.  Achieving superconductivity in boron-doped diamonds by ion implantation has previously been impeded by damage formed when using conventional ion implantation methods.  We observe boron concentrations of up to ~10^22/cm^3 after directing a petawatt laser-driven boron ion pulse onto diamond samples. The resulting high boron concentration leads to the emergence of a superconducting phase, characterized by critical transition temperatures, T_c, of ~0.5 K.  T_c value are dependent on detailed laser-ion doping conditions. T_c values obtained to date by laser-ion doping are much lower than T_c values that have been observed in diamonds that had been doped with boron during crystal growth (up to ~10 K).  Our results show that intense ion pulses from laser-acceleration can heat, excite and dope semiconductors to levels that have been out of reach for more conventional methods.  We will discuss strategies for further process optimization to reach higher T_c values that have been predicted for highly boron doped diamond and integration of superconducting structures with quantum emitters [1, 2].

1. K. Jhuria, et al., “Programmable quantum emitter formation in silicon”, Nat Commun 15, 4497 (2024)

2. W. Liu, et al., “Optical and spin properties of nitrogen vacancy centers formed along the tracks of high energy heavy ions”, arXiv:2403.03570