IBM’s Dr. Talia Gershon (Senior Manager, Quantum Research) discusses quantum computing to 5 different people; a child, teen, a college student, a grad student and a professional.

Quantum computing helps calculates things in a different way than regular computers. they operate by new rules. Quantum mechanics is a branch of physics that helps us design with new rules for problem solving.

**Superposition** is the ability of a quantum system to be in multiple states at the same time until it is measured. Quantum superposition is a fundamental principle of quantum mechanics. It states that much like waves in classical physics, any two (or more) quantum states can be added together (“superposed”) and the result will be another valid quantum state; and conversely, that every quantum state can be represented as a sum of two or more other distinct states.

**Quantum entanglement** is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently — instead, a quantum state must be described for the system as a whole.

**Quantum interference** is one of the most challenging principles of quantum theory. Essentially, the concept states that elementary particles can not only be in more than one place at any given time (through superposition), but that an individual particle, such as a photon (light particles) can cross its own trajectory and interfere with the direction of its path.

In quantum computing, a **qubit **or **quantum bit** (sometimes qbit) is a unit of quantum information—the quantum analogue of the classical bit. A qubit is a two-state quantum-mechanical system, such as the polarization of a single photon: here the two states are vertical polarization and horizontal polarization. In a classical system, a bit would have to be in one state or the other.

**Fault tolerance** is the property that enables a system to continue operating properly in the event of the failure of some (one or more faults within) of its components.