Title: Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED
Speaker: Dr. Adam Stokes (University of Manchester)
Abstract: In quantum electrodynamics (QED) each choice of gauge provides different physical definitions of light and matter as quantum subsystems. This gauge-relativity is most evident in the ultrastrong light-matter coupling regime where it can have important implications for effective models that are in common use. In particular, we show that when truncating the material system to two levels, each gauge gives a different description whose predictions vary significantly for ultrastrong-coupling. Quantum Rabi models (QRMs) are obtained through specific gauge choices, but so too is a Jaynes-Cummings model (JCM) without needing the rotating-wave approximation. Analysinga circuit QED setup, we find that this JCM provides more accurate predictions than the QRM for the ground state, and often for the first excited state as well. Thus, Jaynes-Cummings physics is not restricted to light-matter coupling below the ultrastrong limit. Next, we consider time-dependent couplings as required for numerous applications. We show that in the absence of an argument to choose a particular gauge when promoting the coupling parameter to a time-dependent function, the description that results is essentially ambiguous. For sufficiently strong and non-adiabatic interactions, the qualitative physical predictions of final subsystem properties, such as entanglement and photon number, depend on the gauge chosen. This occurs even when the coupling vanishes at the preparation and measurement stages of the protocol, at which times the subsystems are unique and experimentally addressable.
Time: Monday, 1 April 2019, 2:30 pm
Location: Lecture Room, 1st Floor, School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4
Leave a Comment
Posted: 29th March 2019 by George Rogers
Monday 1st April: STP Seminar – Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED
Title: Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED
Speaker: Dr. Adam Stokes (University of Manchester)
Abstract: In quantum electrodynamics (QED) each choice of gauge provides different physical definitions of light and matter as quantum subsystems. This gauge-relativity is most evident in the ultrastrong light-matter coupling regime where it can have important implications for effective models that are in common use. In particular, we show that when truncating the material system to two levels, each gauge gives a different description whose predictions vary significantly for ultrastrong-coupling. Quantum Rabi models (QRMs) are obtained through specific gauge choices, but so too is a Jaynes-Cummings model (JCM) without needing the rotating-wave approximation. Analysinga circuit QED setup, we find that this JCM provides more accurate predictions than the QRM for the ground state, and often for the first excited state as well. Thus, Jaynes-Cummings physics is not restricted to light-matter coupling below the ultrastrong limit. Next, we consider time-dependent couplings as required for numerous applications. We show that in the absence of an argument to choose a particular gauge when promoting the coupling parameter to a time-dependent function, the description that results is essentially ambiguous. For sufficiently strong and non-adiabatic interactions, the qualitative physical predictions of final subsystem properties, such as entanglement and photon number, depend on the gauge chosen. This occurs even when the coupling vanishes at the preparation and measurement stages of the protocol, at which times the subsystems are unique and experimentally addressable.
Time: Monday, 1 April 2019, 2:30 pm
Location: Lecture Room, 1st Floor, School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4
Category: Regular seminars, School of Theoretical Physics News & Events
...obituaries of prominent individuals The manuscript has been preserved in the @Library_RIA since 1883. (3/3) @HistFest #DIASdiscovers #connacht #books
The Annals of Connacht is a vellum manuscript that was written in the mid-16th century. The contents were derived from older annals compiled for the O’Conors of the Connacht and contain an annual record of significant events over 320 years, and... (2/3)
Date: 19 October 1944 Paper: The Irish Press Synopsis: DIAS has been publishing books since it's founding. One such early publication is the edited manuscript of the Annals of Connacht (Annála Connacht) which was edited for the first time by Martin Freeman of DIAS. (1/3)
This work was to help towards the preservation of the Irish Language, to maintain it's continuity with the past, and was to become a resource for teachers to check pronunciation #DIASdiscovers #Irish #Irishlanguage #CelticStudies #Gaelic
The researchers used the International Phonetic Alphabet, slightly modified to represent vowels and consonants of living speech. At that time there were concerns over the deterioration of the Irish language due to the "overpowering influence of English"
Date: 02 June 1943 Paper: The Irish Press Synopsis: In 1943, a phonetic investigation led by Brian Ó Cuív, Risteárd B. Breathnach and Tomás de Bhaldraithe of DIAS would begin the first systematic scientific recording of the varied sounds of modern Gaelic speech.
Happy Birthday! twitter.com/thecelticist/s…
The papers were 1) Affine Field Theory: conservation identitites and relation to Weyl and Eddington 2)The Union of the three fundamental fields (Gravitation, Menson, Electromagnetism) Which went on to secure worldwide acclaim. #DIASdiscovers
Date: 01 December 1943 Paper: The Irish Press Headline: Two Papers by Dr. Schroedinger Synopsis: 1943 was a busy year for Schroedinger. Not only did he deliver the "What is Life?" Lectures in @tcddublin in February in November he delivered two papers in the @RIAdawson (1/2)
Available to buy on the DIAS bookshop: books.dias.ie/index.php?main… (5/5) #DIASdiscovers #celtic #studies #twopatricks
"In the lives of St. Patrick, the two saints are invariably fused into one", said Prof. O'Rahilly in his lecture. The lecture was a condensation from O’Rahilly’s book “The two Patricks: a lecture on the history of Christianity in fifth-century Ireland”. (4/5)
He was known by his first name Patricius, which in later times would lead to confusion as he was succeeded by another apostle of the same name (Saint Patrick or Patricius in Latin). (3/5)
He spoke on "Palladius and Patrick". Palladius was the first bishop of the Christians of Ireland. (2/5)
Date: 21st March 1942 Paper: The Irish Press Headline: Palladius and Patrick | School Of Celtic Studies Lecture Synopsis: The first public lecture under the auspices of the School of Celtic Studies was delivered in Trinity College by Professor T. F. O'Rahilly in 1942. (1/5)
As part of our ongoing participation in the @HistFest we decided to take a look into the Irish Newspaper Archives and see where DIAS made it into print over the last 80 years. There were so many articles, the hardest part was selecting what we would post. We hope you enjoy!
@AReillyFailte @CultureNight @VisitDublin Thanks Antoinette! Glad you enjoyed 😊