How do you write a simple program for a D-Wave device?

[quantumadmin]

To write a simple program for a D-Wave device, you can use the D-Wave Ocean software development kit (SDK), which provides the necessary tools and libraries for interacting with D-Wave quantum computers. Here's a step-by-step guide to writing a simple program:

Install the D-Wave Ocean SDK: Start by installing the D-Wave Ocean SDK, which includes the necessary libraries and tools for programming D-Wave devices. Detailed installation instructions can be found in the official documentation provided by D-Wave Systems.

Import the required modules: In your Python program, import the required modules from the D-Wave Ocean SDK. These typically include dwave.cloud for connecting to the D-Wave cloud services, and dimod for defining and working with binary quadratic models.

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from dwave.cloud import Client
import dimod

Connect to the D-Wave cloud: Establish a connection to the D-Wave cloud service using your D-Wave API token. This token can be obtained by signing up for an account on the D-Wave Leap platform. Replace 'YOUR_API_TOKEN' with your actual API token

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# Establish a connection to the D-Wave cloud
client = Client.from_config(token='YOUR_API_TOKEN')

Define the problem: The D-Wave quantum computer solves optimization problems, specifically binary quadratic models. Define your problem as a binary quadratic model using the dimod library. This involves specifying variables, their biases, and interactions.

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# Define the problem as a binary quadratic model
bqm = dimod.BinaryQuadraticModel({'x': -1, 'y': 2}, {('x', 'y'): 3}, 0.0, dimod.BINARY)

In this example, we have two variables 'x' and 'y', with biases of -1 and 2 respectively. The interaction between 'x' and 'y' is set to 3.

Submit the problem to the D-Wave solver: Use the D-Wave cloud client to submit the problem to a D-Wave solver. Choose the desired solver based on your requirements and the available resources. The solver's name can be obtained from the D-Wave Leap platform.

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# Submit the problem to a D-Wave solver
solver = client.get_solver()
response = client.submit(bqm, solver)

Retrieve the results: Once the problem has been solved by the D-Wave solver, retrieve the results. This includes the best solution and its associated energy.

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# Retrieve the results
best_solution = next(response.samples())
energy = response.data_vectors['energy'][0]
print("Best Solution:", best_solution)
print("Energy:", energy)

This code retrieves the best solution found and its corresponding energy value.

That's it! You have written a simple program to solve an optimization problem using a D-Wave quantum computer. You can further customize your program, explore different problem formulations, and leverage additional features provided by the D-Wave Ocean SDK.