Nitrogen-vacancy center is a deep defect in diamond. Its energy level structure helps to initialise its pure spin state in room temperature through optical pumping and rotate its state on a Bloch sphere through application of controlled microwave pulses . Lifetime of a superposition state is limited by pure dephasing caused by interactions with a bath of a few hundred randomly distributed C-13 nuclear spins, naturally present in diamond and coupled to the central qubit with dipolar interaction. The shape of decoherence as a function of total evolution time strongly depends on distribution of those nuclei in the lattice. A number of effects, observed in these systems, can be attributed either to spins closest to the NV center or the remainder of weakly coupled bath spins treated as a source of noise. In room temperature, the state of nuclear bath is completely mixed. However, recently a number of experimental results showed successful polarisation of few spins closest to the NV center. Such a partially polarised state can be investigated in a variety of fundamentally interesting directions around the physics of decoherence, such as qubit-environment entanglement  or quantum Darwinism observed through formation of Spectrum Broadcast Structures . References:  Doherty, M. W., Manson, N. B., Delaney, P., Jelezko, F., Wrachtrup, J., and Hollenberg, L. C. L., The nitrogen-vacancy colour centre in diamond. Physics Reports, 528, 1–45 (2013)  Roszak, K., Kwiatkowski, D., and Cywiński, Ł., How to detect qubit-environment entanglement generated during qubit dephasing. Physical Review A, 100, 022318 (2019)  Kwiatkowski, D., Cywiński, Ł., Korbicz, J., Emergence of classicality for NV centers interacting with dynamically polarised nuclear environment, to appear on arXiv in July 2020. ______________________________________________ Zoom meeting details Topic: Quantum Information and Quantum Computing Working Group Time: June 18, 2020, 04:00 PM Warsaw Join Zoom Meeting: QIQCWG-ZOOM Meeting ID: 922 2710 3826Password: bQ,mfjpB! If you encounter any problems with connecting to the Zoom meeting, please email firstname.lastname@example.org directly.