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