Summary Table¶
- EPR Analysis — Master Summary Table: All EPR output parameters consolidated — one
row per parameter, sorted by category
Core EPR
# |
Category |
Parameter |
Symbol |
Unit |
Optimal Value |
Good Range |
Acceptable Range |
Worst Value |
Physical Significance |
Improvement Strategy |
|---|---|---|---|---|---|---|---|---|---|---|
1 |
Core EPR |
Junction Participation Ratio |
p_J |
— |
0.90–0.99 |
0.80–0.99 |
0.50–0.79 |
< 0.30 |
Sets anharmonicity & qubit nonlinearity |
Increase pad size, reduce gap to substrate |
2 |
Core EPR |
Resonator Junction Participation |
p_J^res |
— |
< 1×10⁻³ |
< 1×10⁻² |
1×10⁻²–5×10⁻² |
> 0.10 |
Determines Purcell T_1 limit |
Increase qubit-resonator detuning |
3 |
Core EPR |
ZPF Voltage across Junction |
V_zpf |
µV |
10–50 µV |
5–100 µV |
1–200 µV |
< 0.5 µV |
Governs qubit-photon coupling |
Optimise mode volume and pad geometry |
4 |
Core EPR |
ZPF Phase |
varphi_zpf |
rad |
0.1–0.5 rad |
0.05–0.6 rad |
0.6–0.9 rad |
> 1.0 rad |
Validity of dispersive approximation |
Reduce anharmonicity target or redesign |
5 |
Core EPR |
Anharmonicity (EPR) |
alpha / 2pi |
MHz |
150–350 MHz |
100–400 MHz |
50–99 MHz |
< 30 MHz |
Gate speed and leakage limit |
Lower E_J / E_C ratio; smaller junction |
6 |
Core EPR |
Dispersive Shift chi |
chi/2π |
MHz |
0.5–3 MHz |
0.1–5 MHz |
0.01–0.09 MHz |
< 0.01 MHz |
Readout contrast |
Adjust g/|Δ| ratio via geometry |
7 |
Core EPR |
Cross-Kerr ZZ |
zeta_ij / 2pi |
MHz |
< 0.01 MHz |
< 0.10 MHz |
0.10–0.50 MHz |
> 1.0 MHz |
Always-on 2Q gate error |
Tunable coupler; echo sequences |
Qubit Performance
# |
Category |
Parameter |
Symbol |
Unit |
Optimal Value |
Good Range |
Acceptable Range |
Worst Value |
Physical Significance |
Improvement Strategy |
|---|---|---|---|---|---|---|---|---|---|---|
8 |
Qubit Performance |
Energy Relaxation T_1 |
T_1 |
µs |
> 500 µs |
100–500 µs |
10–99 µs |
< 1 µs |
Hard limit on gate fidelity |
Reduce dominant loss channel from EPR |
9 |
Qubit Performance |
Coherence Time T2* |
T2* |
µs |
> 300 µs |
100–300 µs |
20–99 µs |
< 10 µs |
Practical dephasing limit |
Reduce flux/charge noise; surface cleaning |
10 |
Qubit Performance |
Qubit Quality Factor |
Q_q |
— |
> 10⁷ |
10⁶–10⁷ |
10⁵–10⁶ |
< 10⁴ |
Universal figure of merit |
Reduce all participation-weighted losses |
11 |
Qubit Performance |
Single-Qubit Gate Fidelity |
F_1Q |
% |
> 99.9% |
99.5–99.9% |
99.0–99.4% |
< 98% |
Surface-code threshold |
Increase T_1/T2; optimise DRAG pulses |
12 |
Qubit Performance |
Two-Qubit Gate Fidelity |
F_2Q |
% |
> 99.5% |
99.0–99.5% |
97.0–98.9% |
< 95% |
2Q error correction threshold |
Reduce ZZ via tunable coupler design |
13 |
Qubit Performance |
E_J / E_C Ratio |
E_J / E_C |
— |
50–100 |
40–120 |
20–39 |
< 10 |
Charge noise protection |
Increase shunt capacitance C_S |
Resonator & Coupling
# |
Category |
Parameter |
Symbol |
Unit |
Optimal Value |
Good Range |
Acceptable Range |
Worst Value |
Physical Significance |
Improvement Strategy |
|---|---|---|---|---|---|---|---|---|---|---|
14 |
Resonator & Coupling |
Resonator Frequency |
omega_r / 2pi |
GHz |
6.5–8.5 GHz |
5–10 GHz |
3–5 GHz |
< 2 GHz |
Dispersive regime requirement |
Adjust resonator length/capacitance |
15 |
Resonator & Coupling |
Resonator Internal Q |
Q_int |
— |
> 10⁵ |
10⁴–10⁵ |
10³–10⁴ |
< 500 |
Readout SNR and back-action |
Improve substrate and metal quality |
16 |
Resonator & Coupling |
Coupling Strength g / 2pi |
g / 2pi |
MHz |
50–150 MHz |
20–200 MHz |
5–19 MHz |
< 2 MHz |
Sets chi and readout bandwidth |
Adjust coupling capacitor geometry |
17 |
Resonator & Coupling |
Purcell Decay Rate |
γ_P/2π |
kHz |
< 1 kHz |
1–10 kHz |
10–100 kHz |
> 500 kHz |
T_1 limit via resonator |
Add Purcell filter; increase detuning |
18 |
Resonator & Coupling |
Residual ZZ Static |
zeta_ZZ / 2pi |
kHz |
< 10 kHz |
< 100 kHz |
100–500 kHz |
> 1 MHz |
Conditional phase error |
Tunable coupler; frequency detuning |
Loss & Dissipation
# |
Category |
Parameter |
Symbol |
Unit |
Optimal Value |
Good Range |
Acceptable Range |
Worst Value |
Physical Significance |
Improvement Strategy |
|---|---|---|---|---|---|---|---|---|---|---|
19 |
Loss & Dissipation |
Bulk Substrate Loss Tangent |
tan delta_bulk |
— |
< 1×10⁻⁷ |
< 1×10⁻⁶ |
1×10⁻⁶–1×10⁻⁵ |
> 1×10⁻⁴ |
Bulk energy dissipation |
Use float-zone Si or sapphire |
20 |
Loss & Dissipation |
Metal-Substrate Interface Loss |
tan delta_MS |
— |
< 1×10⁻³ |
< 3×10⁻³ |
3×10⁻³–1×10⁻² |
> 5×10⁻² |
Dominant TLS loss channel |
Ion mill before deposition; clean surfaces |
21 |
Loss & Dissipation |
Surface Participation (MS) |
p_MS |
— |
< 5×10⁻⁴ |
< 2×10⁻³ |
2×10⁻³–1×10⁻² |
> 5×10⁻² |
Weights MS interface loss to T_1 |
Wider gaps; ground plane design |
22 |
Loss & Dissipation |
TLS-Limited Q |
Q_TLS |
— |
> 3×10⁶ |
10⁶–3×10⁶ |
10⁵–10⁶ |
< 10⁴ |
TLS bath limitation |
Surface treatment; new barrier materials |
23 |
Loss & Dissipation |
Seam Loss Rate (3D) |
gamma_seam / 2pi |
kHz |
< 1 kHz |
< 5 kHz |
5–50 kHz |
> 200 kHz |
3D cavity assembly limit |
Indium sealing; tighter tolerances |
Junction Parameters
# |
Category |
Parameter |
Symbol |
Unit |
Optimal Value |
Good Range |
Acceptable Range |
Worst Value |
Physical Significance |
Improvement Strategy |
|---|---|---|---|---|---|---|---|---|---|---|
24 |
Junction Parameters |
Josephson Inductance |
L_J |
nH |
5–20 nH |
2–50 nH |
50–200 nH |
> 500 nH |
Sets qubit frequency |
Junction area and J_c control |
25 |
Junction Parameters |
Josephson Energy |
E_J / h |
GHz |
10–50 GHz |
5–100 GHz |
100–500 GHz |
> 1 THz |
Qubit spectrum with EC |
Barrier thickness and area |
26 |
Junction Parameters |
Charging Energy |
E_C / h |
MHz |
150–350 MHz |
100–500 MHz |
500–1000 MHz |
> 2 GHz |
Anharmonicity and charge sensitivity |
Shunt capacitor area tuning |
27 |
Junction Parameters |
Junction Loss Tangent |
tan delta_J |
— |
< 3×10⁻⁶ |
< 1×10⁻⁵ |
1×10⁻⁵–1×10⁻⁴ |
> 1×10⁻³ |
Intrinsic junction T_1 limit |
ALD AlOx; crystalline barriers |
Simulation
# |
Category |
Parameter |
Symbol |
Unit |
Optimal Value |
Good Range |
Acceptable Range |
Worst Value |
Physical Significance |
Improvement Strategy |
|---|---|---|---|---|---|---|---|---|---|---|
28 |
Simulation |
Eigenfrequency Convergence |
Delta f / f |
ppm |
< 5 ppm |
< 50 ppm |
50–500 ppm |
> 1000 ppm |
Accuracy of all extracted parameters |
More refinement passes; finer mesh |
29 |
Simulation |
Energy Error |
Delta U / U |
% |
< 0.1% |
< 0.5% |
0.5–2% |
> 5% |
Bounds participation ratio error |
Increase mesh density at interfaces |
30 |
Simulation |
Participation Sum Check |
sum p |
— |
0.99–1.01 |
0.97–1.03 |
0.93–1.07 |
< 0.90 or > 1.10 |
Simulation completeness check |
Include all eigenmodes up to 20 GHz |
Total Parameters: 30