A different, more powerful way of computing
Since the 1940s, the rules of computing haven't changed. Computers have continued to get smaller and faster year after year, but their fundamental operations remain the same. They still obey the laws of information processing, and process information by performing operations on bits. Quantum computers manipulate qubits instead of bits. With superposition and entanglement, the states of multiple qubits become very complex. By harnessing these complex states, quantum computers will be able to solve many problems much faster than today’s computers.
How to build a quantum computer
The idea of quantum computing works on paper, but we must be able to build one. This is much easier said than done. The difficulty comes from two opposite requirements:
The computer must be completely isolated from the world around it to protect the fragile state of the qubits;
We must be able to interact with the qubits to control them.
We need to find the right system that balances these requirements. Several prototypes of quantum computers already exist. Since they are not yet advanced enough to offer an advantage over digital computers, we are only at the dawn of the quantum age.
When to use a quantum computer
Unlike advances in digital computing, which add memory capacity or increase the speed of the processor, quantum computing dramatically alters how we solve problems at the fundamental level. Algorithms have to be re-designed from the ground up, and figuring out which problems benefit from using a quantum computer remains an active field of study.
There are many problems where quantum computers are expected to be no better than digital computers. For example, there is no evidence that a quantum computer will be better at running a word processor than a digital computer. Other problems are “easy” for digital computers already, such as multiplying two numbers together.
However, for certain problems, quantum computers can offer strong advantages. While multiplying two numbers together is easy for a digital computer, the reverse process (factoring) is much harder. Even the world’s most powerful supercomputers would take years to factor a 400-digit number. In 1994, Peter Shor proved that a large and robust quantum computer would be able to find those factors exponentially faster.
Quantum algorithms have also been discovered for tasks such as search and optimization, and are waiting for the right hardware to be run on. There are likely many more quantum algorithms that haven’t been discovered yet.
Who is building a quantum computer?
At the Institute for Quantum Computing (IQC), researchers are pushing boundaries and exploring novel approaches to the theoretical and experimental development of quantum computers.
Theory-based research focusing on algorithm development opens up many possible applications of a quantum computer, and helps further our understanding of complex quantum systems and networks. Read more (PDF) about the theory that drives quantum systems and networks.
In the lab, experimental research provides a glimpse into future applications of quantum computers. Researchers are investigating different types of quantum computing platforms, including trapped atoms, trapped ions (PDF), superconducting circuits, and nanoscale spintronics.
Already, some research developments are moving from the whiteboard or lab to the marketplace, and quantum startups are emerging. One example is Quantum Benchmark, co-founded by IQC faculty members Joseph Emerson and Joel Wallman, who recognized the immediate need for software capable of measuring, mitigating and correcting errors in a quantum computer. Read more about their mission to enable quantum computers to solve real-world problems.
IQC faculty member Jonathan Baugh takes a semiconductor approach to building single electron devices, one possible platform for building a scalable quantum computer.