Technique - (3) Deterministic single-ion implantation with on-chip single-ion detection

Type: Fabrication

Description: Counted, spatially registered implantation of single donors/dopants using integrated detector electrodes to confirm each ion stop event.

Department(s)/lab(s): School of Physics | Melbourne Ion Implantation and Single Ion Group (Jamieson) @ UMelb
Summary:

Jamieson's group built the counted single-ion implantation capability that underpins every donor spin qubit made at UNSW and Melbourne: individual P, Sb or Bi ions are implanted into silicon through a nanoscale aperture while on-chip detector electrodes register the electron-hole pairs from each ion stop event, so the number and position of dopants is known rather than assumed. Recent directions extend this to high-atomic-number donors for nuclear-spin qudits, to colour-centre creation in diamond and silicon carbide by counted implantation, and to characterising the damage and charge environment those ions leave behind. The work is fabrication-forward but its scientific content is single-particle detection metrology. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — his contribution is upstream: the deterministic creation and validation of the very spin defects whose ensembles are later interrogated by DEER and nanoscale NMR at pT/sqrt(Hz).

Department(s)/lab(s): School of Physics | Electronic and Condensed Matter Physics Group (McCallum) @ UMelb
Summary:

McCallum works on the materials and detector physics of donor qubits in silicon and colour centres in diamond and silicon carbide: defect engineering by ion implantation and annealing, characterisation of the resulting spin coherence, and — most relevant to a sensing postdoc — the development of superconducting and semiconductor detectors capable of registering single implanted ions with near-unit efficiency, which is what turns implantation from a statistical process into a deterministic one. He also works on near-surface colour centres, where surface termination and Fermi-level control set the achievable coherence. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — his group supplies the near-surface, coherence-optimised spin ensembles that DEER, nanoscale NMR and T1-relaxometry protocols at pT/sqrt(Hz) sensitivity actually depend on.

Department(s)/lab(s): School of Electrical Engineering and Telecommunications | Fundamental Quantum Technologies Laboratory (Morello) @ UNSW
Summary:

Morello heads the Fundamental Quantum Technologies Laboratory and is the person who first read out the spin of a single electron, and then a single nucleus, in silicon. Current directions: high-spin donors (antimony-123, with eight nuclear levels) used as qudits and as sensors of local strain and electric field; nuclear acoustic resonance, in which a strain wave rather than a magnetic field drives the nuclear spin; engineered decoherence experiments as tests of quantum foundations; and precision tomography of multi-qubit donor registers. The group's donors are among the longest-coherence solid-state spins known (seconds for nuclei). Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — a single-donor nuclear spin in silicon is functionally an NV centre with better coherence and worse readout: the same DEER, dynamical-decoupling and nuclear-register protocols apply, and the group's high-spin qudit work is aimed at exactly the multi-level sensing enhancements that the NV community is now chasing. Preferred attribute present: sensitivity and coherence, not fabrication, are the limiting variables here.