Tensor network simulator (TN1) - Amazon Braket

Tensor network simulator (TN1)

TN1 is an on-demand, high-performance, tensor network simulator. TN1 can simulate certain circuit types with up to 50 qubits and a circuit depth of 1,000 or smaller. TN1 is particularly powerful for sparse circuits, circuits with local gates, and other circuits with special structure, such as quantum Fourier transform (QFT) circuits. TN1 operates in two phases. First, the rehearsal phase attempts to identify an efficient computational path for your circuit, so TN1 can estimate the runtime of the next stage, which is called the contraction phase. If the estimated contraction time exceeds the TN1 simulation runtime limit, TN1 does not attempt contraction.

TN1 has a runtime limit of 6 hours. It is limited to a maximum of 10 (5 in eu-west-2) concurrent quantum tasks.

TN1 results

The contraction phase consists of a series of matrix multiplications. The series of multiplications continues until a result is reached or until it is determined that a result cannot be reached.

Note: Shots must be > 0.

Result types include:

  • Sample

  • Expectation

  • Variance

For more about results, see Result types.

TN1 is always available, it runs your circuits on demand, and it can run multiple circuits in parallel. To learn more, see Compare simulators.

Simulators support all gates in the Braket SDK, but QPU devices support a smaller subset. You can find the supported gates of a device in the device properties.

Visit the Amazon Braket GitHub repository for a TN1 example notebook to help you get started with TN1.

Best practices for working with TN1

  • Avoid all-to-all circuits.

  • Test a new circuit or class of circuits with a small number of shots, to learn the circuit’s "hardness" for TN1.

  • Split large shot simulations over multiple quantum tasks.