Interferometric stabilization for a narrowband source of entangled photons

Pušavec, Žiga (author), Kaltenbaek, Rainer (mentor)

The thesis investigates the vibrational noise affecting the stability of the narrowband source of entangled photons we are currently developing. We will use cavity-enhanced spontaneous parametric downconversion in combination with an adapted Michelson interferometer to produce polarization entangled photon pairs. Because the quality of the generated entanglement will directly depend on the quality of the interferometric stability achieved, we will have to implement an active stabilization of the interferometer and the cavities used. This thesis analyses the vibrational noise present in our lab to guide us in the practical implementation of these stabilization mechanisms. For that purpose, we have constructed an adapted Michelson interferometer of the same kind and similar dimensions as we will use in the actual source. After optimising the interference visibility we collected time traces of the interferometer output power under varying environmental conditions. Analysing the corresponding power density spectra allows us to pinpoint the source of individual noise peaks. This will be essential for the optimisation of the design and the performance of our entangled photon source. From the collected data we conclude that the piezoelectric elements we plan to use should be adequate for stabilising the source against the vibrations encountered in our lab. In particular, the amplitude of the path-length changes in the interferometer as well as the frequencies of the most prominent noise peaks are well within the available range of the piezoelectric elements we will use.

• Language: English
• Keywords: entanglement, Michelson interferometer, noise spectrum, quantum communication, quantum optics, vibrations, stabilization, nonlinear optics
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2020
• PID: 20.500.12556/RUL-121509
• COBISS.SI-ID: 31475715
• Publication date in RUL: 13.10.2020

Secondary language

• Language: Slovenian
• Title: Interferometrična stabilizacija za ozkopasovni vir prepletenih fotonov

Abstract

V magisteriju sem raziskal, kako prisotnost vibracij vpliva na stabilnost ozkopasovnega vira prepletenih fotonov, ki ga trenutno razvijamo. Vir bo na osnovi resonatorsko ojačanega procesa spontanega parametičnega zmanjševanja frekvence v kombinaciji s prirejenim Michelsonovim interferometrom proizvedel pare polarizacijsko prepletenih fotonov. Ker bo kvaliteta prepletenosti direktno odvisna od dosežene stabilnosti interferometra, bomo morali vključiti tudi aktivno stabilizacijo interferometra in resonatorjev. Tekom magisterija sem analizal vibracije, ki so prisotne v našem laboratoriju. To nas bo vodilo pri dejanski implementaciji stabilizacijskega postopka. Za določitev spektrov vibracijskega šuma smo postavili prirejen Michelsonov interferometer, katerega postavitev in dimenzije so primerljive z interferometrom, ki ga bomo uporabili v samem viru. Po prvotni optimizaciji vidljivosti interference smo izmerili časovne sledi izhodne moči interferometra pod različnimi zunanjimi pogoji. Primerjava spektrov pridobljenih sledi nam je omogočila določitev izvora posameznih karakterističih vrhov v posameznih spektrih šuma. Ti podatki bodo ključni za optimizacijo postavitve in delovanja našega vira prepletenih fotonov. Iz pridobljenih meritev ugotavljamo, da bodo piezoelektrični elementi, ki jih želimo uporabiti, primerni za stabilizacijo interferometra in resonatorjev proti vibracijam, ki so prisotne v našem laboratoriju. To trdimo predvsem na osnovi tega, da so relativne spremembe dolžine interferometra in glavne vibracijske frekvence povsem v območju, ki je dosegljivo našim piezoelektričnim elementom.

• Keywords: prepletenost, Michelsonov interferometer, spekter šuma, kvantna komunikacija, kvantna optika, vibracije, stabilizacija, nelinearna optika