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.

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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