Quantum Information

In quantum mechanics, quantum information is physical information that is held in the “state” of a quantum system. The most popular unit of quantum information is the qubit, a two-level quantum system. However, unlike classical digital states (which are discrete), a two-state quantum system can actually be in a superposition of the two states at any given time.

Quantum information differs from classical information in several respects, among which we note the following:

It cannot be read without the state becoming the measured value.

An arbitrary state cannot be cloned.

The state may be in a superposition of basis values.

However, despite this, the amount of information that can be retrieved in a single qubit is equal to one bit. It is in the processing of information (quantum computation) that a difference occurs.

The ability to manipulate quantum information enables us to perform tasks that would be unachievable in a classical context, such as unconditionally secure transmission of information. Quantum information processing is the most general field that is concerned with quantum information. There are certain tasks which classical computers cannot perform “efficiently” (that is, in polynomial time) according to any known algorithm. However, a quantum computer can compute the answer to some of these problems in polynomial time; one well-known example of this is Shor’s factoring algorithm. Other algorithms can speed up a task less dramatically ‑ for example, Grover’s search algorithm which gives a quadratic speed-up over the best possible classical algorithm.

16. Make a questionnaire to the text and interview your partner on the problems raised in the text.

17. Sum up the text using the key words, word combinations and the topical sentences.

18. Express your attitude to the facts given in the text. You may use the following phrases:

– It is full of interesting information…

– I find the text rather / very cognitive…

– I’ve learnt a lot …

– I don’t agree with …

19. Say which facts presented in the text you’ve already been familiar with (already known).

20. Give your point of view on the possibility of using the information presented in the text in your future profession.

Part C

21. Look through the following text, define the information presented in it and entitle the text.

22. Scan the following text and say what problem is described in it.

TextC

In physics, a quantum (plural: quanta) is the minimum unit of any physical entity involved in an interaction. An example of an entity that is quantized is the energy transfer of elementary particlesofmatter (called fermions) and of photonsand otherbosons. The word comes from theLatin “quantus”, for “how much”. Behind this, one finds the fundamental notion that a physical property may be “quantized”, referred to as “quantization”. This means that the magnitude can take on only certain discrete numericalvalues, rather than any value, at least within a range. There is a related term ofquantum number.

A photon, for example, is a single quantum of light, and may thus be referred to as a “light quantum”. The energy of anelectron bound to an atom (at rest) is said to be quantized, which results in the stability of atoms, and of matter in general.

As incorporated into the theory of quantum mechanics, this is regarded by physicists as part of the fundamental framework for understanding and describing nature at the infinitesimal level, for the very practical reason that it works. It is “in the nature of things”, not a more or less arbitrary human preference.

23. Say where the presented information can be used.

24. Speak on one of the following points to your partner:

a) the minimum unit of any physical entity;

b) a single quantum of light.