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Fundamentals

01 /Quantum computers with magical advantage? 02 /Bra-ket notation 03 /Born rule 04 /Bloch sphere 05 /Measurement operators 06 /Experimental and theoretical measurements 07 /How to measure in any basis 08 /State decomposition 09 /Why every maximally entangled state is secretly a Bell state 10 /Coherence 11 /Relaxation 12 /Quantum materials: the environment of a qubit 13 /Introduction to quantum error correction (QEC) 14 /Multiqubit systems 15 /Multiqubit gates 16 /Entanglement 17 /Measuring multiqubit systems 18 /Superdense coding 19 /Teleportation 20 /Entanglement swapping

Relaxation

You may have already heard that qubits do not preserve their state or information indefinitely. Often the environment causes the qubit to decohere (see the video about (de)coherence). Another way for a qubit to lose its information is through relaxation, a concept that Ph.D. student Jonas Helsen (QuTech) will introduce in the video below.

Prerequisite knowledge

 

Further thinking

Suppose that you have full control over your system and on the architecture behind your quantum states. What should you change about the two quantum states for a single qubit to increase your relaxation time to infinity?

Solution

Further reading

If you want an extensive insight on quantum relaxation, take a look at the chapter Quantum Theory of Relaxation (Density Matrix Theory and Applications, Blum K., 1996). This is an excellent way to dive into the subject.

  • Blum K. (1996) Quantum Theory of Relaxation. In: Density Matrix Theory and Applications. Physics of Atoms and Molecules. Springer, Boston, MA