Quantum physics exploits the bizarre world of quantum mechanics, which apparently defies natural laws, allowing things to be in two places and to travel faster than light. Quantum computers will actually take advantage of these properties and allow systems to be developed that can perform seemingly impossible tasks.

In this SFI Community Lecture, scientist Christopher Monroe explains the basics of quantum mechanics, and how they can be applied to developing quantum computers, which have no fundamental limits.

Key message: Despite the complexity, don’t worry about not understanding quantum physics, just get comfortable with it and think about how to develop quantum computation.

Watch some of the highlights:

12:00 Miniaturization of transistors on computer chips will reached a physical limit in a few decades, because we cannot go to a smaller scale than a single atom: what are we going to do then?

13:50 When we get down to the single atom, the laws of quantum mechanics take over, opening up the new world of quantum computing.

16:05 The golden rules of quantum mechanics.

17:45 Rule #1: Quantum bits (qubits) are waves and can be in superposition: i.e. two states at the same time, each with a certain weighting.

21:15 Rule #2: Objects like atoms can be in two places at the same time as long as you do not look at them. If you do, the object will probably change into the state with the highest weighting.

30:30 Two qubits, each with two possible superpositions, can be entangled so that a change in state in one (e.g. by measuring it) is reflected in the other, instantly, no matter how far apart they are.

35:10 The amount of information a quantum system has increases exponentially as the number of qubits increases: 1 qubit can store two numbers, 2 qubits can store four numbers, 3 qubits eight, etc. This allows parallel processing using all the numbers at the same time: the basis of quantum computing.

38:30 Quantum computers may be best working on problems where a single output depends on all the inputs, such as optimizing complex processes, like molecular systems, autonomous driving and quantum cryptography.

44:00 How do you run a quantum computer? At the moment with really exotic platforms. One is superconducting circuits, which allow electrical currents to run in two directions at the same time. This will allow qubits to be stored in the system. The other way is even more exotic, using individual atoms suspended above a conventional chip as qubits to perform quantum computations with lasers.

51:10 There is a gap between the research world and industry in applying quantum computing. The National Quantum Initiative of the United States seeks to bridge that gap.