System Model H2 Emulators¶
Default Noise Model Parameters¶
Default Settings 
H21E 
General 

Qubits (Statevector) 
32 
Qubits (Stabilizer) 
56 
Connectivity 
alltoall 
Parallel 2qubit operations 
4 
Wasm Enabled 
True 
Physical Noise 

1Qubit Fault Probability (p1) 
2.9e05 
2Qubit Fault Probability (p2) 
0.00128 
BitFlip Measurement Probability (0 outcome) (p_meas) 
0.0005 
BitFlip Measurement Probability (1 outcome) (p_meas) 
0.0025 
Crosstalk Measurement Fault Probability (p_crosstalk_meas) 
7.4e06 
Initialization Fault Probability (p_init) 
4e05 
Crosstalk Initialization Probability (p_crosstalk_init) 
9.6e06 
Ratio of 1Qubit Spontaneous Emission to p1 (p1_emission_ratio) 
0.32 
Ratio of 1Qubit Spontaneous Emission in 2Qubit Gate to p2 (p2_emission_ratio) 
0.48 
Dephasing Noise 

Quadratic Dephasing Rate (quadratic_dephasing_rate) 
0.043 
Linear Dephasing Rate (linear_dephasing_rate) 
0.0028 
Coherent to Incoherent Factor (coherent_to_incoherent_factor) 
2.0 
Arbitrary Angle Noise Scaling 

Fit Parameter 1 (przz_a) 
1.518 
Fit Parameter 2 (przz_b) 
0.241 
Fit Parameter 3 (przz_c) 
1.518 
Fit Parameter 4 (przz_d) 
0.241 
Polynomial (przz_power) 
1.0 
Performance¶
The performance of the System Model H2 Emulator is measured in comparison to the H2 hardware. With the inclusion of an accurate and uptodate noise model, the System Model H2 Emulator provides a detailed representation of System Model H2 output, operating on a GPU backend. Because of the memory requirements, a slowdown in the number of HSystem Quantum Credits (HQCs) processed in an hour is observed for state vector emulations using 25 qubits or more. The difference in processing time is due to the higher number of qubits combined with the realistic physical noise model of System Model H2 performing a state vector emulation. To estimate the amount of time the emulation will take for state vector emulation, users can use the guideline in Figure 1 in conjunction with the total HQCs for their quantum program. It is generally recommended that users perform state vector emulations with less than 28 qubits. Though it is dependent on the submitted circuit, the execution speed of the System Model H2 hardware is generally higher than the emulator with qubit counts at 28 qubits or more.
Accuracy is verified at Quantinuum by comparing emulator and hardware outputs. Users should be aware that System Model H2 has a more complex trapping geometry than System Model H1. In comparing the H2 emulation to H2 quantum computer results, users may experience a larger discrepancy than experienced comparing System Model H1 emulators to H1 quantum computers. System Model H2 error models will mature over time. In the case of exceptional or unexplained variance, users should contact Quantinuum technical support at QCsupport@quantinuum.com to discuss the circuit and results.
Job Execution¶
Jobs submitted with large shot counts are automatically divided into appropriately sized chunks of smaller shot counts in a method called chunking. Chunking allows for a more incremental distribution of emulation resources to users and an increased flexibility in the management of long running jobs. The number of shots in a chunk is dynamically chosen by the runtime and varies with the complexity of the circuit.