Quantum Computing

Coherent control of decoherence

10 September 2019

Optical approaches to qubits and theoretical insights into coherent control.

Control of molecular reaction directs vibronically excited molecular systems into specific reaction pathways. Failure through such molecular control through laser selective excitation arises from decoherence and dephasing of coherence. Minimizing decoherence is also an important challenge towards realizing quantum computing and quantum information. Typical molecular vibrations occur in picoseconds. So it is important to have control parameters in femtoseconds. Population transfer in molecules involves multiple states besides the radiative coupled two labels which undergo quantum interferences resulting in decoherences. Coupling to the non radiative channels can however be minimized to robustly controlled decoherence through destructive quantum interference between the multiple excitation pathways. Thus a useful quantification of controllability can be identified in terms of two label of character in a multilevel system through density matrix evaluation of coherent character of quantum states. Only a synergy of molecular dynamics and spatio-temporal control of molecules embodies the future of quantum information and computing. It turns out that the very oddly separated areas become connected. Because of that Quantum computing on very odd end gets connected because there also you need 100% controllability as well as 100% both spatial and temporal controllability. And we want to do with optics only. Now light has many more implications. You can actually encode light by informing, putting in data. So there are some data communication issues also which we can bring in, which is generally not what we basically work on. Our data communication only stops at the point that we have informed the molecule what to do. We are not using that as an electrical data communication scheme any more. We had started that at some point of time but now we have moved into more into informing the molecule business. Now the molecule is supposed to take it further and that is the quantum aspect. Sometimes we are not interested in to see the take it further part. We are very happy with when we inform the molecule and get a response from it.

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