Circuit Cavity QED with Macroscopic Solid-State Spin Ensembles PDF
Preview Circuit Cavity QED with Macroscopic Solid-State Spin Ensembles
Springer Theses Recognizing Outstanding Ph.D. Research Stefan Putz Circuit Cavity QED with Macroscopic Solid-State Spin Ensembles Springer Theses Recognizing Outstanding Ph.D. Research Aims and Scope The series “Springer Theses” brings together a selection of the very best Ph.D. theses from around the world and across the physical sciences. Nominated and endorsed by two recognized specialists, each published volume has been selected foritsscientificexcellenceandthehighimpactofitscontentsforthepertinentfield of research. For greater accessibility to non-specialists, the published versions includeanextendedintroduction,aswellasaforewordbythestudent’ssupervisor explainingthespecialrelevanceoftheworkforthefield.Asawhole,theserieswill provide a valuable resource both for newcomers to the research fields described, and for other scientists seeking detailed background information on special questions. Finally, it provides an accredited documentation of the valuable contributions made by today’s younger generation of scientists. Theses are accepted into the series by invited nomination only and must fulfill all of the following criteria (cid:129) They must be written in good English. (cid:129) ThetopicshouldfallwithintheconfinesofChemistry,Physics,EarthSciences, Engineeringandrelatedinterdisciplinary fields such asMaterials,Nanoscience, Chemical Engineering, Complex Systems and Biophysics. (cid:129) The work reported in the thesis must represent a significant scientific advance. (cid:129) Ifthethesisincludespreviouslypublishedmaterial,permissiontoreproducethis must be gained from the respective copyright holder. (cid:129) They must have been examined and passed during the 12 months prior to nomination. (cid:129) Each thesis should include a foreword by the supervisor outlining the signifi- cance of its content. (cid:129) The theses should have a clearly defined structure including an introduction accessible to scientists not expert in that particular field. More information about this series at http://www.springer.com/series/8790 Stefan Putz Circuit Cavity QED with Macroscopic Solid-State Spin Ensembles Doctoral Thesis accepted by TU Wien, Vienna, Austria 123 Author Supervisor Dr. StefanPutz Dr. JohannesMajer Department ofPhysics TU Wien,Atominstitut Princeton University Vienna Princeton, NJ Austria USA ISSN 2190-5053 ISSN 2190-5061 (electronic) SpringerTheses ISBN978-3-319-66446-0 ISBN978-3-319-66447-7 (eBook) DOI 10.1007/978-3-319-66447-7 LibraryofCongressControlNumber:2017950034 ©SpringerInternationalPublishingAG2017 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringerInternationalPublishingAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland To Stephanie ’ Supervisor s Foreword Hybrid quantum systems have gained a lot of interest as future quantum tech- nologies.Thehopeisthattwodifferentquantumsystemscanbecombinedandthat the resulting system profits from advantages of the individual systems. Therewith one intends to pool the strength of different technologies and realize improved quantum devices. The thesis presented by Stefan Putz aims at exploring hybrid quantum devices using superconducting circuits and spin systems, in particular nitrogen-vacancy color centers in diamond. He tried to combine the advantages of superconducting devices, like low losses and exibility with the benefits of the nitrogen-vacancy center, such as the long coherence times and confinement in a host crystal. In the first two sections, Stefan Putz lays out the theoretical foundations for the thesis. Therein he summarizes the relevant literature and illustrates the relevant physics with analogies like the mass on a spring system or the LC circuit. One of the major results of the thesis is the experimental demonstration of the cavity protection effect. Stefan Putz studied the dynamics of a superconducting cavity strongly coupled to an ensemble of nitrogen-vacancy centers in diamond. He experimentally observed how decoherence induced by inhomogeneous broadening canbesuppressedinthestrong-couplingregime,aphenomenonthatisnowknown as“cavityprotection”.Continuingonthisproject,StefanPutzdevelopedascheme to engineer long-lived coherent states in a hybrid system. This scheme was suc- cessfully implemented and improved the coherence times by orders of magnitude. Remarkably, this strongly coupled system performs better than the two individual subsystems. Therefore, this experiment is the first one to live up to the promise of hybrid quantum systems and marks a milestone in the field. In Chap. 7 Stefan Putz demonstrates that hybrid systems can also be used to study nonlinear phenomena. In particular, the hybrid system shows amplitude bistabilityandallowsobservingthetimedynamicsconveniently.Hedemonstratesa vii viii Supervisor’sForeword critical slowing down of the cavity population on the order of several tens of thousandsofseconds—atimescalemuchlongerthanobservedsofarforthiseffect. ThethesisofStefanPutzpresentsseveralimportantadvancesinthefieldofhybrid quantum systems. Therefore, I am convinced that it will be an important reference for future experiments and novel quantum devices. Vienna, Austria Johannes Majer July 2017 Abstract Hybrid quantum systems are one of the most promising implementations offuture quantumcomputation,communication,andsimulationdevices.Thesetechnologies willhaveamajorimpactonsocietyandindustryandheraldthestartofanewage. However, in the early stages of this development, crucial technological limitations have to be addressed and solved. As one part of this giant puzzle, this thesis examines the basic phenomena occurring when interfacing macroscopic spin ensembleswithasingle-mode cavity.Understandingtheseunderlyingprinciplesis keyinthepossibleimplementationofquantummemoriesbasedonsolid-statespin ensembles. The hybrid solid-state quantum system studied in this thesis consists of a superconducting microwave cavity strongly coupled to an ensemble of electron spinshostedbynitrogen-vacancycentersindiamond.Oneofthemainresultsofthe experimentscarriedoutdemonstrateshowthetotaldecoherenceratescalesinthese systems. As is shown the collective enhanced coupling strength allows the sup- pressionofspindephasinginducedbyinhomogeneousspinbroadening.Thiseffect isknownas“cavityprotectioneffect”andthetotaldecoherenceratescaleswiththe collective cavity spin interaction strength. The hybridization acts beneficially on the system coherence time. However, thesetimescanbedrasticallyimprovedbyspectralholeburning,beyondthenatural limitattainablebythe“cavityprotectioneffect”.Theobservedlong-livedcoherence trulylivesuptothepromiseofhybridsystemstoperformbetterthanitsindividual subcomponents. This demonstrates that dark states can be used to coherently exchange energy between the cavity and spin ensemble. These engineered dark states are used to induce coherent Rabi oscillations and a first step is made toward the implementation of a solid-state microwave frequency comb. Additionally, this system is a versatile tool for studying strong nonlinear dynamics.Suchaneffectisamplitudebistability,whichhasnotbeenobservedina ix x Abstract microwave solid-state spin ensemble coupled to a single-mode cavity so far. This engineered hybrid system approach opens up the possibility for a new route to cavity QED experiments beyond the standard Dicke and Tavis-Cummings model, no only also for truly long-lived quantum memories, solid-state microwave fre- quency combs and optical-to-microwave quantum transducers.
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