28.06 Conferences in May and June 2017
In May and June 2017 I had the pleasure to attend many interesting conferences:
- Quantum 2017: From Foundations of Quantum Mechanics to Quantum Information and Quantum Metrology & Sensing, May 7-13, 2017, Turin, Italy.
- International Mathematical Conference on Function Theory dedicated to the centenary of A.F. Leont'ev, May 24-27, 2017, Ufa, Russia.
- 14th Central European Workshop on Quantum Information Processing (CEQIP 2017), May 31 - June 3, 2017, Smolenice, Slovakia.
- 24th Central European Workshop on Quantum Optics, June 26 - 30, 2017, Lyngby, Denmark.
18.06 Visit in Turku 2017
It was a pleasure to work in the University of Turku for a period June 5-18 and collaborate with Teiko Heinosaari on generalized probabilistic theories, and with Jyrki Piilo on divisibility of quantum dynamical maps and collision models.
22.03 Incompatibility of quantum and not only quantum observables
Developing Teiko Heinosaari's ideas, we have quantified the intrinsic noise content of an observable in a general probabilistic theory and derived a noise content inequality for incompatible observables. We have applied the derived inequality to standard quantum theory, the quantum theory of processes, and polytope state spaces. The noise content for positive operator-valued measures takes a particularly simple form and equals the sum of minimal eigenvalues of all the effects. We have illustrated our findings with a number of examples including the introduced notion of reverse observables.
S. N. Filippov, T. Heinosaari, L. Leppajarvi. Necessary condition for incompatibility of observables in general probabilistic theories. Phys. Rev. A 95, 032127 (2017), E-print arXiv:1609.08416 [quant-ph]
10.02 Measurement-induced dynamics
Recently, we have considered a quantum system dynamics caused by successive selective and non-selective measurements of the probe coupled to the system. For the finite measurement rate \tau^-1 and the system-probe interaction strength \gamma we derive analytical evolution equations in the stroboscopic limit \tau -> 0 and \gamma^2 \tau = const, which can be considered as a deviation from the Zeno subspace dynamics on a longer timescale T ~ (\gamma^2 \tau)^-1 >> \gamma^-1. Though the repeatedly measured probe evolution is frozen in the case of projective rank-1 selective measurements, the system evolution is not frozen! In fact, the system dynamics is non-linear in this case, and we derive the effective non-Hermitian Hamiltonian for such an evolution. The deduced non-linear dynamics may find applications in quantum amplifiers. Moreover, the system dynamics is analyzed for selective stroboscopic projective measurements of an arbitrary rank, when both the system and the probe evolve non-trivially. In the case of non-selective measurements, we derive the semigroup dynamics of the system-probe aggregate and find the particular form of the dissipator. Both non-linear and decoherent effects become significant at the timescale T ~ (\gamma^2 \tau)^-1, which is illustrated by a number of physical examples (Heisenberg interaction of spin particles, partial SWAP operations in quantum optics).
I. A. Luchnikov, S. N. Filippov. Quantum evolution in the stroboscopic limit of repeated measurements. Phys. Rev. A 95, 022113 (2017), E-print arXiv:1609.05501 [quant-ph]
11.01 Recent publications
F. Benatti, D. Chruscinski, S. Filippov. Tensor power of dynamical maps and positive versus completely positive divisibility. Phys. Rev. A 95, 012112 (2017), E-print arXiv:1610.04634 [quant-ph]
S. N. Filippov, K. Yu. Magadov. Positive tensor products of qubit maps and n-tensor-stable positive qubit maps. J. Phys. A: Math. Theor. 50, 055301 (2017), E-print arXiv:1604.01716 [quant-ph]
G.G. Amosov, S.N. Filippov. Spectral properties of reduced fermionic density operators and parity superselection rule. Quantum Information Processing 16, 1 (2017), doi:10.1007/s11128-016-1467-9, E-print: arXiv:1512.01828 [quant-ph]
11.12 Autumn conferences 2016
In autumn 2016 there were 2 fruitful conferences in my country:
59th MIPT Scientific conference, November 23-28, 2015, Moscow, Russia. My talk: Non-unitary maps and selective measurements in quantum tomography. Talks by students: (i) V.V. Frizen, S.N. Filippov, Two-qubit entangled states robust to amplitude damping noises, (ii) D.V. Kolobova, S.N. Filippov, Decomposition of non-unital qubit channels.
Ufa International Mathematical Conference, September 27-30, 2016, Ufa, Russia. My talk: Non-linear quantum dynamics induced by measurements. Talks by students: (i) I.A. Luchnikov, Dynamics of interacting spin chains in collisional model, (ii) K. Yu. Magadov, Entanglement-breaking fermionic quantum channels.
02.07 Summer conferences 2016
In summer 2016 I had a chance to attend three interesting conferences:
International Conference on Algebra, Analysis and Geometry, June 26 – July 2, 2016, Kazan, Russia. Talk: 2- and 3-tensor-stable positive qubit maps (presented by K.Yu. Magadov)
13th Central European Quantum Information Processing Workshop, June 16-19, 2016, Valtice, Czech Republic. Talk: Positive tensor products of qubit maps and 2-tensor-stable positive qubit maps [Presentation PDF, 4.63 MB]
48th Symposium on Mathematical Physics "Gorini-Kossakowski-Lindblad-Sudarshan Master Equation - 40 Years After", June 10-12, 2016, Torun, Poland. Poster: Non-linear dynamics induced by successive rank-r selective measurements (together with I.A. Luchnikov) [Poster PDF, 1.16 MB]
06.06 Visit in Turku
It was a pleasure to work for 2 weeks in the University of Turku and collaborate with Teiko Heinosaari on quantum incompatibility, and with Jyrki Piilo and Sabrina Maniscalco on visualization of k-P-divisible quantum dynamical maps.
31.12 Review of news for the year 2015
This web-page looks quite old fashioned, doesn't it?
You're right, it's getting older.
Here is the summary of 2015 news: my primary position is now in the Laboratory of quantum information theory at MIPT (at that web page you can find some recent activities related with my work), there were great conferences in Suzdal, Torun, and Lapland last year (the latter one should not be called conference, however!). Scientific work was spreaded, and now it is time to gather stones together. Teaching is all right, and I give a full course of Quantum mechanics as a lecturer in 2016.
You definitely have many questions, I hope to meet you in person to answer them.
16.09 PPT-inducing, distillation-prohibiting, and entanglement-binding quantum channels
The new paper is avalable at arXiv:1409.4036 [quant-ph]
Entanglement degradation in open quantum systems is reviewed in the Choi-Jamiolkowski representation of linear maps. In addition to physical processes of entanglement dissociation and entanglement annihilation, we consider quantum dynamics transforming arbitrary input states into those that remain positive under partial transpose (PPT-inducing channels). Such evolutions form a convex subset of distillation-prohibiting channels. A relation between the above channels and entanglement-binding ones is clarified. An example of the distillation-prohibiting map Ф(х)Ф is given, where Ф is not entanglement binding.
09.05 Entanglement sensitivity to signal attenuation and amplification
Recent paper written in collaboration with Mario Ziman is now available at arXiv:1405.1754 [quant-ph]
In this paper, we analyze general laws of continuous-variable entanglement dynamics during the deterministic attenuation and amplification of the physical signal carrying the entanglement. These processes are inevitably accompanied by noises, so we find fundamental limitations on noise intensities that destroy entanglement of gaussian and non-gaussian input states.
23.12 Chemistry of quantum entanglement dynamics
Considering multipartite entanglement as a chemical compound opens a new view on the entanglement dissipative evolution. In fact, the particles of environment represent nothing else but the solvent in which the entanglement compound dissociates! The solvent can act on the whole compound (global quantum noise) or particular elements of the compound (local quantum noise). The differences between these two mechanisms are in the presense of clustering stages in the case of global noise, when particles reassemble to form almost equal bipartitions, tripartions, etc.
More info: S. N. Filippov, A. A. Melnikov, and M. Ziman. Dissociation and annihilation of multipartite entanglement structure in dissipative quantum dynamics. Phys. Rev. A 88, 062328 (2013), E-print arXiv:1310.4790 [quant-ph], Download <<PDF>>
16.09 Revealing noise tolerance of quantum entanglement
Promising advances of quantum information technologies rely on the physical phenomenon of entanglement, a particular form of correlations exhibited by composite systems. After being created, the entanglement typically decreases due to unavoidable external noises. To fight with this undesirable effect, scientists have developed quaint methods to maintain correlations such as error correction and entanglement concentration protocols, etc. However, the nature can hardly be deceived, so if the noise level exceeds some fundamental limit, then the entanglement is lost without any chance to be resuscitated by local operations. In our paper [S.N. Filippov and M. Ziman, Bipartite entanglement-annihilating maps: Necessary and sufficient conditions, Phys. Rev. A 88, 032316 (2013)], we find the fundamental limit of such entanglement annihilation for any type of physical noisy evolution. The obtained result is crucial for determining the ultimate length of quantum communication lines.
Links to the paper: http://pra.aps.org/abstract/PRA/v88/i3/e032316 (restricted access), http://arxiv.org/abs/1306.6525 (free access)
09.06 10th Central European Quantum Information Processing Workshop
This year, CEQIP was held in Valtice, Czech Republic. The participants, organization, scientific and social activities (and the venue of course) created a very nice atmosphere reflected in some photos. Our team "Friday" (which sounds quite interesting in Finnish) took part in the cipher game and was the third to solve the final riddle. BTW, guess the solution!
As to science, you can look at our poster (it is self-explaining).
25.05 PhD defense
On May 25, 2012 I successfully defended my PhD thesis entitled "Quantum states and dynamics of spin systems and electromagnetic field in the tomographic-probability representation."
I would like to sincerely thank all my friends, relatives, and colleagues for their kind help and confidence!
29.11 Conference autumn 2010
This fall was full of different conferences on a wide range of topics concerning more or less my scientific interests. It was my pleasure to take part and give reports at the following ones:
- International Conference on Quantum Information and Computation
- 6th International SemOI Workshop "Nanoscaled Semiconductor-on-Insulator Materials, Sensors, and Devices"
- III Nanotechnology International Forum RusNanoTech 2010
- 53rd Conference of Moscow Institute of Physics and Technology 'Modern problems of fundamental and applied sciences'
The detailed information including abstracts, posters, and presentations is available in section Curriculam Vitae.
09.10 2 years and 8 months of awaiting for an article in "Proceedings of MIPT" gone!
It is very nice when something reminds about the work you have done long time ago. Indeed, I am very proud to be a co-author of the article in the journal "Proceedings of MIPT" which has been peer reviewed, processed, and finally published 2 years and 8 months after submission. This paper is based on my Bachelor Thesis and deals with infrared photodiodes. To be exact, the title is "Investigation of charge transfer mechanisms in HgCdTe photodiodes". I must apologize to foreigners because the article is written in Russian and is not translated into English. However, readers (if any) who are interested in this work can approach me with a request for translation without hesitation. If this is the case, I will do my best to get them acquainted with the results we have obtained.
I am very grateful to the supervisor of my Bachelor research, Prof. Konstantin Olegovich Boltar', and greatly appreciate his assistance in theoretical studying of narrow-band semiconductors and, certainly, many experimental skills that I learnt during 2006-2007 (cryostat technique and data processing). So this article is in honour of Prof. Boltar'!
For detailed information about the article and abstract click the title of this piece of news.
The article is available here [pdf, 771kB].
21.08 Mutually unbiased bases: tomography of spin states and star-product scheme
In this article, a star-product scheme for a full set of mutually unbiased bases is established.
Abstract. Mutually unbiased bases (MUBs) are considered within the framework of a generic star-product scheme. We rederive that a full set of MUBs is adequate for a spin tomography, i.e. knowledge of all probabilities to find a system in each MUB-state is enough for a state reconstruction. Extending the ideas of the tomographic-probability representation and the star-product scheme to MUB-tomography, dequantizer and quantizer operators for MUB-symbols of spin states and operators are introduced, ordinary and dual star-product kernels are found. Since MUB-projectors are to obey specific rules of the star-product scheme, we reveal the Lie algebraic structure of MUB-projectors and derive new relations on triple- and four-products of MUB-projectors. Example of qubits is considered in detail. MUB-tomography by means of Stern-Gerlach apparatus is discussed.
Comments are welcome!
Article is available online at http://arxiv.org/abs/1008.2675
15.07 Quantum computing based on space states without charge transfer
This article is a result of my work in the Institute of Physics and Technology RAS during my master project. In the article, special attention is paid to all necessary procedures for Quantum Computer to operate: qubit structure, initialization, realization of one- and two-qubit operations, 'fighting' with decoherence, and read-out. Qubit structure and encoding of quantum information is quite unusual and we hope you will find them interesting.
Article details: V. Vyurkov, S. Filippov, and L. Gorelik, Quantum computing based on space states without charge transfer, Physics Letters A 374 (2010), pp. 3285-3291.
Link to the article: http://dx.doi.org/10.1016/j.physleta.2010.06.023
27.06 Time evolution of two interacting charge qubits: entanglement and mean-field approach
I am glad to inform you that article entitled "Time evolution of two interacting charge qubits: entanglement and mean-field approach" by Sergey Filippov and Vladimir Vyurkov has finally appeared in the journal Quantum Computers and Computing 9(1), 60-65 (2009). This work was done during my Master Project in the Institute of Physics and Technology of the Russian Academy of Sciences (2007-2009). The full text is available (free access) at the publisher site.
18.06 17th Central European Workshop on Quantum Optics (CEWQO'2010)
It was a great honour for me to take part in the 17th Central European Workshop on Quantum Optics held on June 6-11 in St. Andrews, Scotland, UK. At the conference, I have presented a poster "Inverse spin-s portrait method: Representation of qudit states by probability vectors and Spin tomography" by me and Prof. Man'ko. If you are interested in it, you can click <<abstract>> and <<poster>>.
27.05 Philosophy of Science: Quantum Information Theory
It is my pleasure to inform you that my final exam on philosophy of science has been passed successfully. My project on this subject concerns the history and philosophical aspects of Quantum Information Theory and is available here [pdf,419kB,in Russian].
26.05 "Last Ring" Day of the year 2010 in Licee #11 "PhysTech"
Once a year there is a moment when I and my schoolpupils have to say goodbye to each other. I must admit that this Day is joyful and sad at the same time. But "life is life", so let us keep nice memories of those two years in our mind!
28.11 MIPT Conference
My contribution to the 52th Scientific Conference "Modern problems of fundamental and applied sciences" organized by the Moscow Institute of Physics and Technology. Abstracts of talks and presentations are presented.