NV-Center Diamond Quantum Thermometer (2D)

Sample Conditions

True temperature T 300.0 K

Bias field B_z 0.0 mT

Averaged sweeps N 16

Measurement

Measured D(T)

2870.0 MHz

Inferred T

300.0 K

Error vs true T

0 mK

Mean |error|, last 40 shots

0 mK

How it works

A nitrogen-vacancy (NV) center is a substitutional nitrogen atom next to a missing carbon in diamond. Its ground state is a spin-1 triplet with a zero-field splitting D between the m_s=0 and m_s=±1 sublevels, driven and read out optically (ODMR):

D(T) = D₀ − a·(T − T₀)
D₀ = 2870.0 MHz,  T₀ = 300 K,  a = 0.0742 MHz/K

Optically-detected fluorescence vs microwave freq f:
PL(f) = PL₀·[1 − C·(L(f−f₋,Γ) + L(f−f₊,Γ))]
f± = D(T) ± γₑ·B_z ,  γₑ ≈ 28.02 MHz/mT (electron spin)

True temperature — the hidden real temperature of the diamond; the sensor never sees this number directly, only the fluorescence dip.
Bias field — a static B_z Zeeman-splits the single dip into a symmetric pair around D(T), visible as the two m_s=±1 sublevels separating in the energy diagram; their midpoint still reports D(T) cleanly.
Averaged sweeps N — each sweep is shot-noise limited; averaging N repeats shrinks the fluorescence noise by 1/√N. Watch the precision tracker panel: the scatter of single-shot temperature errors visibly tightens as N grows.
The inferred temperature comes from a weighted-centroid fit of the dip(s) in the averaged spectrum, then inverting D(T) — exactly the estimator a real ODMR thermometry pipeline uses.

The lattice panel is a 2D schematic cross-section for orientation — drag to pan, scroll/pinch to zoom. The real defect sits in diamond's 3D cubic lattice; none of the thermometry physics above depends on that dimensionality, since D(T), the Zeeman splitting and the 1/√N noise scaling are properties of the electron spin and the optical readout, not of the crystal's geometry.

Real-world relevance: NV-diamond thermometers already map temperature inside living cells and on chip hotspots at sub-micron resolution and sub-degree precision — a distinct use of the same NV spin that magnetometers exploit via the Zeeman shift instead of this thermal shift of D.

NV lattice (2D schematic)

Spin energy levels

ODMR spectrum

Precision tracker (temperature error)

NV-Center Diamond Quantum Thermometer (2D)