List of talks given by members of my group at APS March Meeting:

Xuexin Xu: B36.00014 Mon 2:06 PM
Arne Schlabes: K41.00012 Tue 5:12 PM
Myself: W41.00008 Thurs 4:48 PM
Manabputra: W41.00009 Thurs 5:00 PM
Alwin van Steensel: Y35.00013 Fri. 10:48 AM
Josephine Pazem: Z36.00012 Fri 1:42 PM

and posters too.

#apsmarch #fzjuelich #rwthaachen

Parasitic-free gate: A protected switch between idle and entangled states

We propose a protected 2-qubit gate composed of two sub-gates that switches between idling and entangling modes. These sub-gates are separated by a large energy barrier. In superconducting circuits, this gate is derived by harnessing microwave driving and coupling modulation. The idle mode decouples qubits and leaves them with highly localized wave functions. The entangled mode, however, makes them interact in absence of the adversarial ZZ interactions. Our theoretical results show that this gate is a promising way to switch on and off a fast and high fidelity 2-qubit interaction. Read further details here

PhD position in my group

The theory groups at the Institute for Quantum Information of the Jülich-Aachen Research Alliance (JARA) are looking for a highly motivated candidate to fill a PhD position over the next few months. The doctoral project will focus on theoretical studies of physical implementations of quantum information processing, such as superconducting qubits, and enabling quantum technologies. The projects will be supervised by Dr. M.H. Ansari and may involve collaborations with leading experimental groups.

Master’s degree (or equivalent) in theoretical condensed matter physics or a related field and proficiency in English are required. Preference will be given to candidates with experience in quantum transport and open quantum systems, but strong candidates from other fields are encouraged to apply.

The application material should include:

• Short letter of motivation (less than a page)
• CV and transcripts
• Contact details (names and emails) of two possible referees

For further information about the group see the group webpage: https://sites.google.com/site/mansari.

To submit an application please email your documents to m.ansari@fz-juelich.de. Review of applications will start immediately and continue until all the position is filled.

New Physics talk

Recently I was invited to give a Quantum Information Seminar at Physics department of Syarcuse University, NY. There was a broad audience from high energy physics to cosmology, quantum chemistry, gravity and black holes and quantum computation, both experimentalists and theorists. My talk was about a new correspondence we found recently between physics and information. Below you can find my abstract, for questions contact me. 

Link to Quantum Information Seminars at Syracuse

New Physics from Quantum Information Theory by Dr. Mohammad Ansari

Jan 17, 2019 at 11:00 AM - 12:00 PM

Room: 202 Physics Bldg.

In quantum physics physical quantities are linear in density matrix, e.g. energy, current, spin, etc. However, this is not the case in quantum information theory as  informational measures are nonlinear functions in density matrix; examples are entropy, fidelity loss, purity, etc.  Is there any way to measure information in the lab using physical quantities? This is an important question that I’ll address in this talk. I’ll present a new correspondence between entropy and physical quantities. I will  discuss how this correspondence may introduce new physics in quantum heat engines, quantum computation, black holes, etc..

Dr. Mohammad Ansari, Julich Research Center, Germany

Host: Britton Plourde. Contact: Yudaisy Salomon Sargenton - phyadmin@syr.edu

Donna Strickland

The lady who taught us nonlinear optics in Waterloo during my PhD studies just received a Nobel Prize in Physics! Dr Donna Strickland is nice, honest, and down-to-earth modest, such that I  could not shamefully believe that she is better than others! She was excellent teacher also and was delivering science very well to students, and always with a taste of sweetness!

Her story of being so humble remind me of the following poem by Emily Dickinson:
I'm Nobody! Who are you?
Are you -Nobody- too?
Then there's a pair of us!
Don't tell! they'd...

...

The institute of Theoretical Nanoelectronics (PGI-2) concerns itself with investigating structure formation in condensed matter, starting on electronic length and time scales while bearing in mind macroscopic consequences. These studies are closely connected in diverse ways with experimental work within the institute, and also with projects in other institutes at Forschungszentrum Jülich.

The main focus of our work is placed on the electronic structure of solids, in particular with regard to their importance in information technology and cooperative phenomena in condensed matter. Research questions here concern dynamic structure formation processes together with the statistical mechanics of order and disorder processes. Special topics in the field of complex fluids deal with the structure and dynamics of soft matter.

We are looking to recruit as soon as possible a

Postdoctoral Researcher in Quantum Information and Thermodynamics

Your Job:

• studying quantum heat engines in presence of enviornmental disturbance
• understanding information-to-work process in superconductiong quantum computational devices
• studying the analogue of fluctuation-dissipation theorem in quantum theory

Your Profile:

• PhD degree (or nearly graduating) in theoretical condensed matter physics or a related field
• Preference will be given to cadidates with background experience in Quantum computation, condensed matter, statistical mechanics, and related Topics. Strong candidates from other fields are encouraged to apply
• Ability and willingness to work in an international, interdisciplinary and distributed teams as well as to assume responsibility

Our Offer:

• a varied and challenging area of ​​responsibility in an interdisciplinary team
• Exciting work setting on an attractive research campus with a very good infrastructure, ideally situated within the city triangle of Cologne, Düsseldorf, and Aachen
• A comprehensive further training programme, including German language courses
• Flexible working hours and various opportunities to reconcile work and family life
• Limited for 1 years with possible longer-term prospects
• Full-time position with the option of slightly reduced working hours
• Salary and social benefits in conformity with the provisions of the Collective Agreement for the Civil Service (TVöD)

Forschungszentrum Jülich aims to employ more women in this area and therefore particularly welcomes applications from women.

We also welcome applications from disabled persons.

See our webpage to apply

Postdoctoral research on Quantum Information and Thermodynamics

Exact correspondences between seemingly different concepts play an important role in all fields of physics. An example is the fluctuation-dissipation theorem, which states that linear response of a system to external driving force corresponds to system fluctuations and this initiated important developments. Owing to technological miniaturization, nowadays quantum systems can be probed and controlled to high accuracy. However, theoretical efforts to identify quantum phenomena in thermodynamics are stalled by the difficulty of defining basic quantum quantities, such as heat flow, entropy production, work, and temperature. Recently using quantum information techniques Nazarov and Ansari developed a new correspondence in physics to extend the fluctuation-dissipation theorem into the realm of quantum systems.

To further study and test this new correspondence the theory group of Jülich-Aachen Research Alliance (JARA) at Peter Grünberg Institute in Germany is looking for highly motivated candidates to fill a postdoc position over the next few months.The project will be supervised by Dr. Ansari, and may involve collaborations with leading experimental groups.

Candidates with a PhD degree (or nearly graduating) in theoretical condensed matter physics or a related field can apply. Preference will be given to candidates with experience in background in quantum computation, condensed matter, statistical mechanics, and related topics, but strong candidates from other fields are encouraged to apply.

The application material should include:

• CV & transcripts
• names & emails of 3 referees

If interested, please submit your files to m.ansari@fz-juelich.de. Review of applications will start in September and will continue until the position is filled.

Exact quantization of superconducting circuits

Another paper on transmon qubits is out. In this paper:

We present a theoretical description for circuits consisting of weak anharmonic qubits coupled to cavity multimodes. We obtain a unitary transformation that diagonalizes harmonic sector of the circuit. Weak anharmonicity does not alter the normal mode basis, however it can modify energy levels. We study two examples of a transmon and two transmons coupled to bus resonator, and we determine dressed frequencies and Kerr nonlinearities in closed form formulas. Our results are valid for arbitrary frequency detuning and coupling within and beyond dispersive regime. (M.H. Ansari)

Full text 

arXiv:1807.00792

Peter Grünberg

Our research institute is named after a 2007 Nobel Laureate: Prof. Peter Grünberg. Sadly I heard that Peter Grünberg passed away today.

Peter Grünberg in 1988 discovered giant magnetoresistance (GMR), for which in 2007 together with Albert Fert received the Nobel prize.

Their discovery allowed the storage capacity of hard drives to be significantly increased and made the miniaturization of storage devices. GMR is the sudden change in electrical resistance of a material, made of alternating ferromagnetic and non-magnetic metal layers, when exposed to large magnetic field. If magnetization of neighbouring layers is parallel, electrical resistance heavily drops, however if antiparallel the resistance goes much much higher.  So this makes a large potential barrier between spin up and spin down, which can be used to code information on such a device.

Quantum Thermodynamics at APS March Meeting (2018)

American Physics Society organises another March Meeting for a week this year again. The venue will be at Los Angeles. There is aninvited session on quantum thermodynamics and information that contains 5 interesting talk by experimental and theoretical physicists. Highly recommended!

On Thursday morning 8-11AM, the following 5 invited speakers will give their talks:

Session R42: Progress in Quantum Thermodynamics
Invited
Sponsoring Units: DQI GSNP
Chair: Mohammad Ansari, Forschungszentrum Julich
Room: LACC 502B

8:00AM - 8:36AM
R42.00001: Progress in Thermodynamics of Superconducting and Hybrid Circuits
Invited Speaker: Jukka Pekola , Jonne Koski , Bayan Karimi , Alberto Ronzani , Jorden Senior , Olli Saira

8:36AM - 9:12AM
R42.00002: Fluctuation Theorem for Many-Body Pure Quantum States
Invited Speaker: Takahiro Sagawa

9:12AM - 9:48AM
R42.00003: Strong coupling quantum thermodynamics and beyond
Invited Speaker: Q. Jens Eisert

9:48AM - 10:24AM
R42.00004: Thermoelectrics of interacting nanosystems - Exploiting fermion-parity superselection instead of time-reversal symmetry

Invited Speaker: Janine Splettstoesser , Jens Schulenborg , Joren Vanherck , Angelo Di Marco , Maarten Wegewijs

10:24AM - 11:00AM
R42.00005: Quantum and Information Thermodynamics: A Unifying Framework Based on Repeated Interactions
Invited Speaker: Massimiliano Esposito

* By the way my own talk will be on the same day, an hour after this session is over, in another room.  I'll give a talk about a new formalism to deal with Transmon-like qubits. More info can be found below:


Session S39: Superconducting Circuits: Modeling
11:15 AM–2:15 PM, Thursday, March 8, 2018
LACC Room: 501B
Sponsoring Unit: DQI
Chair: Antonio Corcoles, IBM T J Watson Res Ctr
12:15 PM–12:27 PM

Abstract: S39.00006 : Effective Hamiltonian in superconducting qubits
Mohammad Ansari 
(Forschungszentrum Juelich)

Qubits with more than two energy levels, such as superconducting transmons, usually are externally driven in order to engineer one and two qubit gates. However due to the presence of higher excited levels the fidelity of the gates requires improvement. Such a system carries a large Hilbert space and recognizing effective qubits requires to use perturbation theory. This puts a lage limitation on the system parameters and interactions. We discuss a method that allows to go beyond regular perturbative limitations and separates classical effects from quantum fluctuations in the Hamiltonian of a weakly-anharmonic qubits. We compare results taken from applying Schrieffer-Wolff transformation, Least action principle, and our method. Our results will become practical tools for experimental efforts in circuit QED.

###
I may prepare a nice poster too to post on the wall, so please feel free to find my poster about a different topic:

#apsmarch

Multiple PhD positions – JARA Institute for Quantum Information (RWTH Aachen & Forschungszentrum Jülich)

The theory groups at the Institute for Quantum Information of the Jülich-Aachen Reasearch Alliance (JARA) are looking for highly motivated candidates to fill multiple PhD positions over the next few months (a DFG-funded position could start as soon as possible).

The doctoral projects will focus on theoretical studies of physical implementations of quantum information processing, such as superconducting and semiconducting qubits, and related enabling quantum technologies. The projects will be supervised by Dr. Ansari, Dr. Catelani, and/or Prof. Hassler, and may involve collaborations with leading experimental groups (IBM, Yale, Aalto, TU Delft).

Master’s degree (or equivalent) in theoretical condensed matter physics or a related field and proficiency in English are required. Preference will be given to candidates with experience in quantum transport, superconductivity, and related topics, but strong candidates from other fields are encouraged to apply.

The application material should include:

• short letter of motivation ( 
• CV & transcripts 
• contact details (names & emails) of two possible referees 

For further information, or to submit an application, please contact one of us by email. Review of applications will start immediately and continue until all the positions are filled.

Mohammad Ansari (m.ansari@fz-juelich.de)
Gianluigi Catelani (g.catelani@fz-juelich.de)
Fabian Hassler (hassler@physik.rwth-aachen.de)


Source: http://www.quantuminfo.physik.rwth-aachen.de/cms/Quantuminfo/Das-Institut/~drkm/Stellenangebote/?lidx=1

Entropy production in a photovoltaic cell

In the everyday world, the amount of disorder, or entropy, in an isolated system can only increase over time. This relation is described by the second law of thermodynamics. This indicates that not all of the energy we provide for a system can be converted into engineered work.

In quantum physics, however, the existence of such a law is obscure. One of the main reasons is that entanglement can dramatically alter the notions of disorder and equilibrium state. Instead of an analogue law, recently a correspondence has been found between entropy production and the statistics of energy transfers in a quantum system.

In my paper published recently at Physical Rev. B I studied how entropy is produced in a quantum heat engine. This helps us to explain how heat is dissipated in the engine. The engine is modelled by four electronic levels resonantly-coupled to thermal heat baths kept at different temperatures. Results show that quantum coherence that is induced by environment can significantly and nonlinearly modify entropy production in the cells. Consequently, the nonlinear entropy production can take place much slower or faster.

This determines under what conditions information in these cells can take a reversal flow from a cold to hot bath.

Ref:  Mohammad H. Ansari, Phys. Rev. B 95, 174302 (2017)
It is available online at https://doi.org/10.1103/PhysRevB.95.174302

Abstract: 

 I evaluate entropy production in a photovoltaic cell that is modeled by four electronic levels resonantly coupled to thermally populated field modes at different temperatures. We use a formalism recently proposed, the so-called multiple parallel worlds, to consistently address the nonlinearity of entropy in terms of density matrix. Our result shows that entropy production is the difference between two flows: a semiclassical flow that linearly depends on occupational probabilities, and another flow that depends nonlinearly on quantum coherence and has no semiclassical analog. We show that entropy production in the cells depends on environmentally induced decoherence time and energy detuning. We characterize regimes where reversal flow of information takes place from a cold to hot bath. Interestingly, we identify a lower bound on entropy production, which sets limitations on the statistics of dissipated heat in the cells.

Another PhD position is available

Job type: PhD
Application deadline: Monday, June 5, 2017
Employer: Peter Gruenberg Institute (PGI-2)

Another PhD position is available to work at Peter Gruenberg Institute (PGI-2) and Juelich-Aachen Research Alliance Institute (JARA) in Forschungszentrum Juelich in Germany. The degree will be granted by RWTH University in Aachen. The student will work with Dr. Mohammad H. Ansari and the project can be started in the Summer or Fall 2017.

The purpose of the project is to develop relations between quantum computing models and physical devices. The project requires that you have basic knowledge of quantum physics and information, e.g. density matrix, decoherence, Bloch equation, correlations, nonequilibrium statistics, quantum information measures, Keldysh techniques, etc. We will collaborate with some theoretical and experimental research groups, such as the research group of Prof. D. DiVincenzo at PGI-2 and Prof. Y. Nazarov in Delft University of Technology.

For full consideration, please apply **as soon as possible** by sending your documents in *ONE pdf file* to "m.ansari AT fz-juelich.de", including:

1. your academic CV,
2. your academic transcripts and the list of publications,
3. a short essay relating your knowledge to recent papers written by Dr. Ansari (no more than 300 words ~ two paragraphs)
4. the names, affiliation, and email addresses of 2 or 3 referees, (make sure they are willing to send letters on time)

Please make sure to choose the following subject for your email: "Ph.D. position at PGI-2"

More updates about the position can be found at: https://sites.google.com/site/mansari

My talks on Entropy-Noise Correspondence

I am back from a loooong long trip into several cities in the US and Canada, where I gave a series of talks about my research.

In my trip to New Orleans, for the first time I saw real palm trees! The city has its own character within its cheesy streets full of excited visitors and free storytelling stations! I was also excited to see Mississippi river, which reminded me one of the cartoons I was watching when I was almost ten: the Adventures of Huckleberry Finn! At APS March meeting I enjoyed meeting some old friends from Japan, the US, Canada, Germany, Holland, Australia, etc, gave a short talk about "information contents of physical interactions" and enjoyed learning new things.

Later I traveled to Canada to give a series of talk in different places and to visit a research group for future collaborations. My schedule was very rich! I started with the University of Toronto, then went to Waterloo to visit and give a talk at the Institute for Quantum Computation (IQC) on how to measure entropy in quantum systems. +

As planned I also visited the Perimeter Institute in Waterloo too, where I got my PhD degree 9 years ago from within its old building, the post office building. The "new" building has changed a lot and now has a wired wing full of offices to somehow compensate its original land-wasting floor map. There were too many new faces there and almost nobody recognised me except a few of present faculty members. There I gave a talk in the quantum foundations seminars about the new entropy-noise correspondence we found last year +

These talks turned out to fall into the interest of two main communities: condensed matter theorists and quantum information theorists.

To provide equal opportunities to those not present in the cities yet like to form and express a judgement, I uploaded a short summary of my presentations here to be accessible to public. Please feel free to review.

M.H. Ansari

Talks

If you happen to be near Aachen this week, come to hear news about entropy. (this link) 

***********************************************************
Quantum information seminar, Mar 09 11:00, Physikzentrum MBP2 116
***********************************************************

SPEAKER: Mohammad Ansari (FZ Jülich)
TITLE: Entropy measurement in quantum systems

ABSTRACT: Entropy is an important measure of information. Being nonlinear in density matrix, its consistent evaluation for a quantum system requires a formalism that allows simultaneous evolution of more-than-one-copy of density matrix. Recently in [MHA and Y. Nazarov, Phys. Rev. B 91, 104303 (2015)] a formalism for such evolutions has been proposed and [MHA and Y. Nazarov, Phys. Rev. B 91, 174307 (2015)] shows that such entropy correspond to physical quantities. Interestingly this correspondence is not equivalent to the second law of thermodynamics. In this talk I describe how to measure entropy flow in a quantum heat engine.

************************************************************

Also next week I am in New Orleans. If you are attending APS March meeting I am going to give a talk in Session L52: Statistics of Ensemble Quantum Systems Wednesday at 11:50 AM in  Room: 399. 

A postdoc/PhD student position

A fully-funded postdoc/PhD student position is available to work at Peter Gruenberg Institute (PGI-2) in Forschungszentrum Juelich, near Aachen in Germany. For students the degree will be granted by RWTH university in Aachen. The researcher will work with Dr. Mohammad H. Ansari. The project can be started in the Summer or Fall 2017.

The purpose of the project is to develop the relations between quantum information theory and physics. For this aim we recently developed a new formalism called multiple parallel world technique. Our findings will be used to explore new phenomena in quantum computing, thermodynamics, and photosynthetic complexes in biology. The project requires that you have basic knowledge about quantum physics and information, e.g. density matrix, decoherence, Bloch equation, correlations, nonequilibrium statistics, quantum information measures, Keldysh techniques, etc.

We will collaborate with some theoretical and experimental research groups, such as the research group of Prof. D. DiVincenzo in PGI-2 and Prof. Y. Nazarov in Delft University of Technology, the Netherlands, et. al. The employed researcher will have the opportunity to visit our collaborators.

Everyone (Masters and PhD students and Postdocs) from all around the world are welcome to apply.

For full consideration, please apply as soon as possible, by sending your documents in *ONE pdf file* to "mansari AT gmail DOT com", including:

1. your academic CV,
2. your list of publications,
3. research interests on what makes your past research experience related to quantum thermodynamics, (no more than 300 words ~ two paragraphs)
4. the names, affiliation, and email addresses of 2 or 3 referees, (make sure they are willing to send letters on time)

More information about the research details as well as announcements (e.g. whether the position is still available or not) can be found at:
https://sites.google.com/site/mansari

A newly-published course book by Manoukian

December this year is almost the 10th anniversary of finding new degeneracy in area spectrum and finding heir application. (1,2)

Yesterday I was informed in an email from Springer that some of those results about area quantization have found their way into a  newly-published graduate textbook. Although this is not the first time that somebody writes about what I have done (see footnotes) but this time feels differently because my physics is now a part of a graduate course book.

Here is the book: "Quantum Field Theory II: Introductions to Quantum Gravity, Supersymmetry and String Theory (Graduate Texts in Physics.) written by E.B. Manoukian and published by Springer on September 2016).

I read some parts of it, yet not all, and to my point of view it is quite decent book in the field, well-written and organized, and clear. It provides interesting insights about recent developments in quantum field theory. More importantly it teaches how modern physicists think about quantum foundations, overall a must-read book for graduate students working on quantum field theory.

This is pretty exciting to see that the degeneracy of quantum area spectrum and its physical applications ten years after its discovery are now exercises for young students!

-----
Footnotes:

* D. Oriti, Approaches to Quantum Gravity: Toward a New Understanding of Space, Time and Matter (Cambridge University Press 2009) highlighted my research on black hole and area quantization.
          

* M. Aschwanden, Self-Organized Criticality in Astrophysics: The Statistics of Nonlinear Processes in the Universe (Springer London 2011) highlighted my research on cellular automata, self-organized criticality and nonequilibrium phenomena.

* A section 2.46.3 of the book: The Cosmic Compendium: Black Holes by R. W. Anderson has devoted only to explain my results on black hole.

* The article by L. Smolin, in Physics Today 59 Nov 44 (2006) highlighted some of my results on black holes http://dx.doi.org/10.1063/1.2435646 , etc.

News about entropy

Did you know that you have been calculating entropy incorrectly during your whole life!   This is at least what I claim to be true in a recently published paper titled: "A consistent flow of entropy."

A common approach to evaluate entropy in quantum systems is to solve a master-Bloch equation to determine density matrix and substitute it in entropy definition. However, this method has been recently understood to lack many energy correlators. The new correlators make entropy evaluation to be different from the substitution method described above. The reason for such complexity lies in the nonlinearity of entropy. In this paper we present a pedagogical approach to evaluate the new correlators and explain their contribution in the analysis. We show that the inherent nonlinearity in entropy makes the second law of thermodynamics to carry new terms associated to the new correlators. Our results show important new remarks on quantum black holes. Our formalism reveals that the notion of degeneracy of states at the event horizon makes an indispensable deviation from black hole entropy in the leading order.

This is a my contribution to special issue in Fortschritte der Physik for the Frontiers of Quantum and Mesoscopic Thermodynamics Conference. Link: arXiv:1605.04620

By: Mohammad H. Ansari

Hearing a sound from a billion years ago!

Today is a day for cheering. After many years gravitational waves have been finally reported to have been detected. In two separate detectors, in west and east coasts of the US, almost simultaneously it was detected that earth got shrunk a tiny bit from a gravitational curving pulse. Many researchers have been sweating for decades to make these detectors happen.

Let me explain what has been discovered. An early approval for the theory of general relativity in 60's was based on the following fact: the presence of a heavy object, like our sun, will causes its surrounding spacetime to be curved. This has been observed from the following experiment: the straight path on which light travels in the universe from A to B, if passes adjacent to a heavy object, will bend a bit toward the object, thus the path will not remain a straight path anymore.

Now, consider two heavy objects crazily rotate around one another with a crazy speed (a half of speed of light). Right before they merge they make a lot of ups and downs in the spacetime in between. This turbulence in the very spacetime fibres propagate to others places, similar to how tsunami waves propagate in the ocean. In other words, gravitational field is self-interacting; this means that it sources itself. It curves the space around itself because it carries mass/energy by itself much like a star does.

If the objects are many light years away, the waves passing through the Earth today makes a bit of stretches and squeezes in the radius of earth, something of the size of less than the radius of proton! This has been detected last year at LIGO detectors and today was reported, and peer reviewed already in the PRL.

From what they received we assume that the waves came from two 30-solar-mass black holes curling up around one another in a death spiral, a billion light-years away from us. This is a better-than-expected source for LIGO and sometimes the universe is nice to us!  In fact a billion years ago two heavy stars fell in love with one another and played hand in hand like kids, and today we got a bit of their happy sound!  Doing such an amazing science is similar walking a tightrope between surly curmudgeon and starry-eyed cheerleader. 

  

The last thing to notice: If you are sad you do not get cited more often, apparently Einstein’s prediction of gravitational waves has been cited only a few times!

By: Mohammad H. Ansari

APS March Meeting 2016

I'll be chairing a session in the upcoming American Physics Society March Meeting 2016 in Baltimore, USA. The session is focused on Quantum Information and Thermodynamics.

Below you can find the session information. I invited some notable young scientists whose contribution to quantum physics have been impressive in the last year.

Looking forward to run an impressive focus session!

  http://meetings.aps.org/Meeting/MAR16/Session/R44

 Mohammad H Ansari