A Quantum Leap in Computing

Travis S. Humble, Director, Quantum Computing Institute, Oak Ridge National Laboratory and Megan N. Lilly, Quantum Computing Institute, Oak Ridge National Laboratory

Travis S. Humble, Director, Quantum Computing Institute, Oak Ridge National Laboratory

Exponential growth in computing has revolutionized technical and economic advances across a broad variety of economic sectors: defense, finance, transportation, and many more. But physical limits on this growth, the dreaded end of Moore’s Law, raise questions about how computing will grow in the future. The uncertainty is amplified by the growth in demand arising from large-scale analytics and the increasing size of data centers as well as the costs of securing and storing data in transit and at rest. Meeting these demands will require solutions that are more time and energy efficient, and it is unclear how today’s approaches to computing will meet such requirements. An alternative to address this growing concern is now making headlines, and we give a perspective on why the research behind quantum computing is an exciting possibility for emerging challenges of large-scale computing.

Enter the Quantum Computer

Quantum computing is a new approach to computation that relies on quantum physics to perform calculations. The idea was spurred from insights into how information is stored in atoms, electrons, and photons, which uses features such as superposition, entanglement, and interference. For example, a qubit serves as a quantum analog of a bit that can exist in a superposition of the 0’s and 1’s comprising information. In practice, this creates a probability for either outcome to be observed and the power of quantum computing lies in manipulating those probabilities.

Megan N. Lilly, Quantum Computing Institute, Oak Ridge National Laboratory

Adding qubits gives a multiplicative increase in computational power and provides the basis for exponential growth. This includes the novel resource of entanglement that arises from the correlated behavior between qubits and which has proven to be the basis for a variety of quantum algorithms. Examples of algorithms for modeling and simulations, machine learning, and optimization provide key insights into how much faster quantum computing could solve real-world problems.

A broad, global effort has sought to demonstrate the concepts of quantum computing. The fundamental controllability needed to build quantum computers using individual trapped atoms, photons, and electrons has been established, but these demonstrations have also highlighted the challenges in scaling up qubits in quantity and quality. Today, quantum computers are at a very early stage of development compared to modern computing systems. The few early devices available for research-grade testing are small, expensive, imperfect and restricted to leading research laboratories.

Building Quantum Advantage

The promises offered by quantum computing are two fold. First, quantum algorithms are proven to have theoretical speed ups over best-in-class counterparts for conventional computing. This implies a corresponding payoff in time-to-solution that could be a big win for scalable applications, e.g., database mining and machine learning. The second payoff is the lower energy consumption expected from using both fewer operations and lower energy technologies. The individual atoms and electrons that comprise a quantum computer require considerably less energy to perform calculations and there is a potential energy dividend of several orders of magnitude.

Research groups across industry, academia, and government are now working towards the next major milestone: demonstrating a quantum advantage over conventional computing. Quantum advantage would symbolize when the technology exceeds current capabilities, and it would give a clear indication that work is progressing in the right direction. For example, modeling and simulation of quantum physics is limited by the memory and energy consumption available in modern high-performance computing systems. But a quantum computer offers a natural platform to push pass this physical limitation. Although this achievement will require larger and more polished devices than currently available, clear examples of quantum advantage are within reach of near-term devices.

The Future is Quantum

The effort to develop quantum computing, scale up the hardware, and demonstrate a quantum advantage is accelerating. Software and applications for quantum computing are advancing quickly, spearheaded by open-source initiatives and growing user communities. Performance benchmarks for quantum computers are beginning to emerge that enable comparisons across generations of devices as well as with conventional approaches. Driven by the need for more timely and efficient solutions, we anticipate the long development period for the technology will push our computational capabilities to new heights.