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Quantum Circuit Depth & Fidelity Estimator

Physical quantum processors suffer from gate infidelities that multiply across circuit layers.

Total single-qubit gates (H, X, Rz).

Total entangling gates (CNOT, CZ, iSWAP).

Average single-qubit gate error (e.g. 0.0005 = 99.95% fidelity).

Average two-qubit gate error (e.g. 0.005 = 99.5% fidelity).

Number of time steps/layers in concurrent execution.

Duration of one gate clock cycle.

Calculated Result
75.92%

Circuit Success Fidelity

Total Gate Count

190 gates

Total Runtime

1.250 µs

2-Qubit Ratio

21.1%

Calculation Breakdown

  1. Gate Fidelity ProductF = (1 - ε₁)^150 * (1 - ε₂)^40 = 75.918%
  2. Circuit DurationTime = Depth * Cycle = 50 * 25 ns = 1.250 µs

What Is the Quantum Circuit Depth & Fidelity Estimator?

Quantum circuit depth and fidelity quantify the complexity and survivability of a quantum program against physical errors.

How Does the Quantum Circuit Depth & Fidelity Estimator Work?

Multiplies individual gate success probabilities assuming uncorrelated stochastic Pauli errors.

Quantum Circuit Depth & Fidelity Estimator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

F_{ ext{total}} = (1 - epsilon_1)^{N_1} cdot (1 - epsilon_2)^{N_2}, quad t_{ ext{run}} = ext{Depth} imes t_{ ext{cycle}}

Multiplicative independent gate fidelity and total parallel execution latency.

How to Use the Quantum Circuit Depth & Fidelity Estimator

  1. Enter 1-qubit and 2-qubit gate counts, hardware error rates per gate, circuit depth, and hardware gate cycle time.

Step-by-Step Example Calculation

NISQ Algorithm Execution

Input Values:

singleQubitGates:150
twoQubitGates:40
singleGateErrorRate:0.0005
twoGateErrorRate:0.005
circuitDepth:50
cycleTimeNs:25
Worked Steps: Yields estimated circuit fidelity of 75.8% with execution runtime of 1.25 µs.

Understanding Your Result

Indicates whether the circuit is likely to yield valid measurement signals or devolve into uniform noise.

Factors That Affect the Result

  • Two-qubit gates are typically an order of magnitude more error-prone than single-qubit gates.

When Should You Use This Calculator?

  • VQE and QAOA algorithm compilation, circuit transpilation optimization, and quantum benchmarking.

Assumptions & Limitations

  • Assumes uncorrelated errors; ignores cross-talk, leakage, and idle qubit dephasing during execution.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Stochastic Pauli error model baseline.

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