Measurements and applications of mechanical motion in the quantum limit

Erno Damskägg

Measurements and applications of mechanical motion in the quantum limit

Julkaisun otsikon käännös: Mekaanisen liikkeen mittauksia ja sovelluksia kvanttimekaanisella rajalla

Erno Damskägg

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Mikroskooppisissa systeemeissä esiintyy monia mielenkiintoisia kvanttimekaanisia ilmiöitä, joita ei voida selittää klassisen fysiikan avulla. Kvanttimekaniikka selittää alkeishiukkasten, atomien ja sähkömagneettisten aaltojen ominaisuudet ja niiden kvanttimekaaniset ilmiöt kuten lomittumisen, aaltohiukkasdualismin ja hiukkasten superposition. Makroskooppisessa kokoluokassa kiinteiden aineiden sähköiset ominaisuudet selittyvät kvanttimekaniikan avulla, ja kvanttimekaaniseen koherenssiin liittyviä ilmiöitä havaitaan kokeellisesti supranesteissä ja suprajohteissa. Makroskooppiset kappaleet kuitenkin käyttäytyvät pääasiassa klassisen fysiikan mallien mukaisesti, koska ne menettävät kvanttiluonteensa vuorovaikutuksessa ympäristön kanssa. Mekaaniset värähtelijät sopivat erinomaisesti kvantti-ilmiöiden tutkimiseen makroskooppisissa kappaleissa, koska niiden liikettä voidaan mitata erittäin tarkasti, ja niiden vuorovaikutusta ympäristön kanssa voidaan kontrolloida. Optomekaniikka tutkii valon ja mekaanisten värähtelijöiden välistä säteilynpaineen välittämää vuorovaikutusta. Viimeaikaiset saavutukset alalla ovat mahdollistaneet kvantti-ilmiöiden tutkimisen makroskooppisissa mekaanisissa värähtelijöissä. Esimerkiksi mekaaninen värähtelijä on pystytty jäähdyttämään sen kvanttimekaaniseen perustilaan sekä mikroaaltovärähtelijän että optisen värähtelijän avulla. Tämä väitöskirja käsittelee optomekaanista systeemiä, jossa mikromekaaninen alumiinikalvovärähtelijä on kytketty suprajohtavaan mikroaaltovärähtelijään. Työ keskittyy Heisenbergin epämääräisyysperiaatteen aiheuttamiin ilmiöihin. Periaate johtaa kvanttirajaan, joka rajoittaa kuinka tarkasti tietyt ominaisuusparit voidaan mitata. Harmonisella värähtelijällä on satunnaisliikettä, vaikka se olisi jäähdytetty perustilaan. Tämän takia mekaanisen värähtelijän paikkaa ei voida mitata äärettömän tarkasti. Puristetussa tilassa yksi ominaisuus värähtelijän tilasta voidaan mitata epämääräisyysperiaatteen aiheuttamaa kvanttirajaa tarkemmin toisen ominaisuuden mittaustarkkuuden kustannuksella. Tässä työssä lähes makroskooppisen kappaleen värähtely mitataan puristetussa tilassa. Epämääräisyysperiaatteen takia värähtevän signaalin vahvistaminen lisää mittaukseen kohinaa. Tässä työssä toteutetaan mittausmenetelmä, jossa jättämällä yksi osa signaalista mittaamatta voidaan vahvistaa toinen osa ja mitata se täydellisesti. Työssä totetutetaan myös kahden portin optomekaaninen vahvistin, joka toimii samanaikaisesti taajuusmuuttajana. Lisäksi työssä tutkitaan kahden värähtelijän yhteisvärähtelyitä. Työssä osoitetaan kuinka kahden värähtelijän jatkuvan mittauksen aiheuttama takaisinkytkentä voidaan välttää. Lopuksi kahden mekaanisen värähtelijän liikkeet mitataan lomittuneessa tilassa.

Julkaisun otsikon käännös	Mekaanisen liikkeen mittauksia ja sovelluksia kvanttimekaanisella rajalla
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Ohjaaja	Sillanpää, Mika, Vastuuprofessori Sillanpää, Mika, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-7953-0
Sähköinen ISBN	978-952-60-7954-7
Tila	Julkaistu - 2018
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

optomekaniikka
mekaaniset värähtelijät
kvanttiraja
lomittuminen

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-7954-7Lisenssi: Määrittelemätön

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@phdthesis{a1140fdd47fc4fb1bf2d1145b27ab625,

title = "Measurements and applications of mechanical motion in the quantum limit",

abstract = "Microscopic systems exhibit many intriguing quantum mechanical phenomena which cannot be explained by classical physics. Quantum mechanics has succesfully explained the behaviour of subatomic particles, atoms, and electromagnetic waves where entanglement, wave-particle duality and superposition of particles has been observed. In macroscopic scales, quantum mechanics explains the microscopic origin of electronic properties of solids, and quantum coherence effects are routinely observed in superfluids and superconductors. However, most macroscopic objects behave according to the laws of classical physics due to decoherence effects caused by interaction with the environment. Mechanical systems are ideal for studying quantum behavior of macroscopic objects as they can be measured with high accuracy, and their interaction with the environment can be controlled. Cavity optomechanics studies the interaction between light and mechanical objects through radiation pressure force. Recent developments in the field have made it possible to study quantum behaviour in macroscopic mechanical objects. For example, mechanical oscillators coupled to either microwave or optical light have been cooled to their quantum ground state. This thesis studies a cavity optomechanical system in which micromechanical aluminium membrane resonator is coupled to a superconducting microwave circuit resonator. This work focuses on the phenomena relating to the Heisenberg's uncertainty principle which sets a fundamental limit to the precision in which certain pairs of properties of a system can be measured. Due to uncertainty principle, even if a harmonic oscillator is cooled to the ground state, it still has random motion called the zero-point motion. This sets a fundamental limit on how accurately one can measure the motion of the resonator. In a squeezed quantum state, fluctuations of a quantity can be reduced below this quantum limit, at the cost of increased fluctuations in the pair variable. In this work, motion of a nearly macroscopic object is measured in a squeezed state. Due to uncertainty principle, a measurement amplifying an oscillatory signal always adds noise. However, when information in one part of the signal is lost, one can amplify and measure the other part perfectly. This kind of nearly noiseless phase-sensitive measurement, and squeezing of microwave fields is demonstrated in this work. An optomechanical device that simultaneously performs high-gain amplification and frequency conversion is created. Collective dynamics of a multimode optomechanical system is studied. When measuring the oscillator position continuously, the system is perturbed by the measuring. This can be avoided in quantum back-action evading measurement, which is demonstrated for collective motion of two mechanical resonators. Finally, an entanglement of centre-of-mass motion of two nearly macroscopic objects is created and stabilised.",

keywords = "optomechanics, mechanical resonators, quantum limit, entanglement, optomekaniikka, mekaaniset v{\"a}r{\"a}htelij{\"a}t, kvanttiraja, lomittuminen, optomechanics, mechanical resonators, quantum limit, entanglement",

author = "Erno Damsk{\"a}gg",

year = "2018",

language = "English",

isbn = "978-952-60-7953-0",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "75",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Measurements and applications of mechanical motion in the quantum limit

AU - Damskägg, Erno

PY - 2018

Y1 - 2018

N2 - Microscopic systems exhibit many intriguing quantum mechanical phenomena which cannot be explained by classical physics. Quantum mechanics has succesfully explained the behaviour of subatomic particles, atoms, and electromagnetic waves where entanglement, wave-particle duality and superposition of particles has been observed. In macroscopic scales, quantum mechanics explains the microscopic origin of electronic properties of solids, and quantum coherence effects are routinely observed in superfluids and superconductors. However, most macroscopic objects behave according to the laws of classical physics due to decoherence effects caused by interaction with the environment. Mechanical systems are ideal for studying quantum behavior of macroscopic objects as they can be measured with high accuracy, and their interaction with the environment can be controlled. Cavity optomechanics studies the interaction between light and mechanical objects through radiation pressure force. Recent developments in the field have made it possible to study quantum behaviour in macroscopic mechanical objects. For example, mechanical oscillators coupled to either microwave or optical light have been cooled to their quantum ground state. This thesis studies a cavity optomechanical system in which micromechanical aluminium membrane resonator is coupled to a superconducting microwave circuit resonator. This work focuses on the phenomena relating to the Heisenberg's uncertainty principle which sets a fundamental limit to the precision in which certain pairs of properties of a system can be measured. Due to uncertainty principle, even if a harmonic oscillator is cooled to the ground state, it still has random motion called the zero-point motion. This sets a fundamental limit on how accurately one can measure the motion of the resonator. In a squeezed quantum state, fluctuations of a quantity can be reduced below this quantum limit, at the cost of increased fluctuations in the pair variable. In this work, motion of a nearly macroscopic object is measured in a squeezed state. Due to uncertainty principle, a measurement amplifying an oscillatory signal always adds noise. However, when information in one part of the signal is lost, one can amplify and measure the other part perfectly. This kind of nearly noiseless phase-sensitive measurement, and squeezing of microwave fields is demonstrated in this work. An optomechanical device that simultaneously performs high-gain amplification and frequency conversion is created. Collective dynamics of a multimode optomechanical system is studied. When measuring the oscillator position continuously, the system is perturbed by the measuring. This can be avoided in quantum back-action evading measurement, which is demonstrated for collective motion of two mechanical resonators. Finally, an entanglement of centre-of-mass motion of two nearly macroscopic objects is created and stabilised.

AB - Microscopic systems exhibit many intriguing quantum mechanical phenomena which cannot be explained by classical physics. Quantum mechanics has succesfully explained the behaviour of subatomic particles, atoms, and electromagnetic waves where entanglement, wave-particle duality and superposition of particles has been observed. In macroscopic scales, quantum mechanics explains the microscopic origin of electronic properties of solids, and quantum coherence effects are routinely observed in superfluids and superconductors. However, most macroscopic objects behave according to the laws of classical physics due to decoherence effects caused by interaction with the environment. Mechanical systems are ideal for studying quantum behavior of macroscopic objects as they can be measured with high accuracy, and their interaction with the environment can be controlled. Cavity optomechanics studies the interaction between light and mechanical objects through radiation pressure force. Recent developments in the field have made it possible to study quantum behaviour in macroscopic mechanical objects. For example, mechanical oscillators coupled to either microwave or optical light have been cooled to their quantum ground state. This thesis studies a cavity optomechanical system in which micromechanical aluminium membrane resonator is coupled to a superconducting microwave circuit resonator. This work focuses on the phenomena relating to the Heisenberg's uncertainty principle which sets a fundamental limit to the precision in which certain pairs of properties of a system can be measured. Due to uncertainty principle, even if a harmonic oscillator is cooled to the ground state, it still has random motion called the zero-point motion. This sets a fundamental limit on how accurately one can measure the motion of the resonator. In a squeezed quantum state, fluctuations of a quantity can be reduced below this quantum limit, at the cost of increased fluctuations in the pair variable. In this work, motion of a nearly macroscopic object is measured in a squeezed state. Due to uncertainty principle, a measurement amplifying an oscillatory signal always adds noise. However, when information in one part of the signal is lost, one can amplify and measure the other part perfectly. This kind of nearly noiseless phase-sensitive measurement, and squeezing of microwave fields is demonstrated in this work. An optomechanical device that simultaneously performs high-gain amplification and frequency conversion is created. Collective dynamics of a multimode optomechanical system is studied. When measuring the oscillator position continuously, the system is perturbed by the measuring. This can be avoided in quantum back-action evading measurement, which is demonstrated for collective motion of two mechanical resonators. Finally, an entanglement of centre-of-mass motion of two nearly macroscopic objects is created and stabilised.

KW - optomechanics

KW - mechanical resonators

KW - quantum limit

KW - entanglement

KW - optomekaniikka

KW - mekaaniset värähtelijät

KW - kvanttiraja

KW - lomittuminen

KW - optomechanics

KW - mechanical resonators

KW - quantum limit

KW - entanglement

M3 - Doctoral Thesis

SN - 978-952-60-7953-0

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Measurements and applications of mechanical motion in the quantum limit

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

Sormenjälki

Laitteet

OtaNano

OtaNano – Kylmälaboratorio

OtaNano Nanofab

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