Sampling the tensor network state

The following code example illustrates how to sample the tensor network state (e.g., sampling the final quantum circuit state). The full code can be found in the NVIDIA/cuQuantum repository (here).

Headers and error handling

Define the tensor network state and the desired number of output samples to generate

Let’s define a tensor network state corresponding to a 16-qubit quantum circuit and request to produce 100 output samples for the full qubit register.

Initialize the cuTensorNet library handle

Define quantum gates on GPU

Create a pure tensor network state

Now let’s create a pure tensor network state for a 16-qubit quantum circuit.

Apply quantum gates

Let’s construct the GHZ quantum circuit by applying the corresponding quantum gates.

Create the tensor network state sampler

Once the quantum circuit has been constructed, let’s create the tensor network state sampler for the full qubit register (all qubits).

Configure the tensor network state sampler

Now we can configure the tensor network state sampler by setting the number of hyper-samples to be used by the tensor network contraction path finder.

Prepare the tensor network state sampler

Let’s create a workspace descriptor and prepare the tensor network state sampler.

Allocate the workspace buffer on GPU and setup the workspace

Allocate the required scratch workspace buffer, and provide extra buffer for cache workspace.

Perform sampling of the final quantum circuit state

Once everything had been set up, we perform sampling of the quantum circuit state and print the output samples.

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