Three Truths and the Advent of Hybrid Quantum Computing
By: Murray Thom
Tags: Science, Quantum Cloud, Quantum Computing, Hybrid, Quantum

Ok, but what is quantum-classical hybrid?

Quantum-classical hybrid is the use of both classical and quantum resources to solve problems. A hybrid approach allows developers to exploit the powers of both, today, and reap the benefits of the ongoing acceleration in quantum-computer development tomorrow. As the size of the processors grow, quantum computers promise to provide unrivaled performance at some types of tasks, such as solving certain hard optimization problems.

An example of the benefit of using a hybrid approach can be seen in how Recruit Communications uses quantum computing to optimize ad placement in its prototype application that inputs data from mobile phones and databases. While the quantum computer handles the hard problem of optimizing click-through-rate prediction, classical resources do everything else — from getting user data and communicating with servers, to displaying results. This example of a quantum-classical hybrid workflow is similar to how central processing units (CPUs) in laptops outsource compute-intensive graphics-display processing to a graphics processing unit (GPU). As every business knows, since Ford’s first automobile plant, allocating the tasks of a complex job to specialized resources is an unbeatable strategy.

D-Wave Hybrid provides developers with a Python framework for building a variety of flexible hybrid workflows so quantum and classical resources can be used in parallel to find the optimal solution to your business problem. Other hybrid workflows might use classical resources to find a problem’s hard core and send that to the QPU or break a large problem into smaller pieces that can be solved on a QPU and then recombined.

Next steps

Assess your applications. Begin by searching for bottlenecks in your applications, places where they spend a lot of time solving problems or where they return unsatisfactory results. These applications may be workhorses, but the availability of new data, new computers, or new sensing technology may make them more complex and slower than before.

Ask these key questions. If you answer Yes to some or all of the questions below, your application may benefit from adding quantum computation.

Does your application make binary judgements or answers to a question that are either True or False? (E.g., Did each task meet its deadline? Did network nodes experience failures? Did loans go into default? Did neurons activate? Did the crew make it to the flight?)

Are there relationships and correlations between the inputs? (E.g., Does one missed deadline affect other tasks? Does a failed network node change the load on other nodes? Does a defaulted loan affect the risk to other loans? Which other neurons received the signal through their synapses? Is the crew required for other flights?)

Frame your problem in a form that quantum computers can solve. For quantum computing, as for classical, solving a problem requires that it be formulated in a way the computer and its software understand. The D-Wave quantum computer accepts a problem formulated as a binary quadratic model (BQM), a form of cost function that it solves by minimizing energy. A BQM problem is simply a collection of binary variables with associated linear and quadratic biases. Several examples are available in the D-Wave Ocean documentation.

Deconstruct the problem. Find good solutions to your problem using the different strengths afforded by both quantum and classical computing resources. D-Wave Hybrid provides out-of-the-box hybrid workflows to get you started. As a first step, try Kerberos, a workflow in which D-Wave Hybrid coordinates the work between your laptop’s CPU and the quantum computer to find solutions, such as finding a valid map coloring. You can later use the framework to optimize a hybrid workflow best-suited for your particular problem.

Sign up for Leap to get access to real-time quantum computer. Through Leap, D-Wave’s quantum cloud service, you can try a live quantum computer for free and access a wealth of resources in the Quantum Application Environment (QAE) to get started. Run our demos that introduce the programming model and the types of problems that the quantum computer is well-suited to solve. Try our interactive Jupyter Notebooks that teach you to program. Join a community of like-minded developers.

Download the Ocean SDK and start coding. D-Wave Hybrid is part of the Ocean SDK, the open-source toolset for programming the D-Wave quantum computer. It’s available on GitHub.