A quantum walk is the quantum mechanical analog of a classical random walk, describing the propagation of quantum walkers (photons) through an optical circuit. Because quantum walks generate large-scale quantum superposed states, they can be used for simulating many-body quantum systems and the development of algorithms for quantum computation. Nejadsattari et al. describe the photonic simulation with cyclic quantum systems. With the ability to simulate a variety of different quantum operations and gates, they claim that the versatility of the approach should allow the study of more complex many-body systems.
Intel is taking a slow and steady approach to quantum computing. Competitors like Google may be racing to achieve so-called quantum supremacy, in which a quantum computer outperforms an ordinary one. But Intel's James Clarke has bigger ideas. He leads the firm's quantum computing research team, and says it is looking past near-term goals in order to be the first to make a device with a million qubits, or quantum bits – enough to have a real impact on the world.
That might not sound like much, but in the quantum computing arms race, several groups are edging past one another as they aim to eventually make a universal quantum computer. A group of researchers at the Joint Quantum Institute has created a quantum simulator using 53 quantum bits, or qubits. Earlier this month, IBM announced a 50-qubit prototype, though its capabilities are unclear. With this 53-qubit device, the researchers have done scientific simulations that don't seem to be possible
Quantum computing is an increasingly hot area for research and investment, with corporations like IBM, Google, Alibaba, Intel, and Lockheed Martin launching quantum computing projects aimed at bringing the technology -- meant to speed up the process of solving complex equations -- to commercial viability. In tandem with company investments, the European Union, US, and Chinese governments, among others, are also backing projects aimed at building commercial quantum computers. In the US, NASA, the NSA, and the Los Alamos National Laboratory are all involved in quantum computing projects. And in August this year, China launched the world's first quantum satellite in the quest for more secure communications. However, there are only a small number of private companies in the industry that have been able to raise over $1M, which suggests that commercial application of quantum computers -- for both hardware and software -- is nascent at this point, despite the hype.
A century ago, the quantum revolution quietly began to change our lives. A deeper understanding of the behavior of matter and light at atomic and subatomic scales sparked a new field of science that would vastly change the world's technology landscape. Today, we rely upon the science of quantum mechanics for applications ranging from the Global Positioning System to magnetic resonance imaging to the transistor. The advent of quantum computers presages yet another new chapter in this story that will enable us to not only predict and improve chemical reactions and new materials and their properties, for example, but also to provide insights into the emergence of spacetime and our universe. Remarkably, these advances may begin to be realized in a few years.