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Preface
work embedded in this frame with the aim to achieve a Habilitation in physics. I
could start praising the wonderful and useful achievements that have been enabled
by the evolution of various technologies, which have utilised nanostructuring, electronics and optics together with principles from quantum mechanics, towards what
is nowadays being widely labelled as quantum technologies of the first and second
generation. But what was more important in the first place well before the beginning
of this Habilitation project, was the motivation to dig deep into the principles of
nature and to unravel concepts which may play an important role in the evolution of
our physical realm, referred to as the cosmos in the large scale and the nanocosmos
in the small scale.
Although the tools used throughout one’s life may often not bring closer to us
the furthest distant objects or events, as well as the smallest possible known length
scales or actions attributed to Max Planck’s historic studies, one can indeed shed light
on important aspects of the else hidden world through knowledge-driven actions
fed by enthusiasm and fascination. Solid-state research and particularly the work
with (semiconductor) quantum structures can add considerable knowledge in this
regard, whereas concepts and principles are tested on different, and most importantly,
accessible length scales (also time scales) and environments that not seldom mimic
with unimaginable precision those realms we are fundamentally more interested
in. Often, who studies the small, understands better the large, who explores the
large, reveals the small, and who examines both the small and large, may even
unravel details about the very small. In a physical world full of resonances (eigenstates), excitations (particles), and energy transfer (interactions), this might hold true
even more. Some reasoning from ancient philosophies and cultures might deliver
an interesting access to the building blocks and the fabric of our natural habitat,
e.g. through comparison and imagination. And with an intuition for the meaning
of the Sanskrit expression ‘Aom’ (‘Om/Aum’), perceived to be characterising the
sound of our universe, and the far-eastern ‘Tao’,
1 describing the ‘Nothingness’ and
‘Existence’ of the same origin and the endless cycles of all things in a vital flow,
quantum mechanics being governed by wave mechanics and the uncertainty principle
also lets one remember to adapt to the flow of nature and to tolerate the intangible
in the orchestra play of the universe, while striving for a deeper understanding.
Time is short to touch upon the concept of causality, its philosophical Sanskrit
counterpart ‘Karma’, and the meaningful Kramers–Kronig relations well known
from solid-state physics. By the way, what would the vivid world be like without
time? ‘Time’ manifests itself in the energy exchanges within a system governed by
interacting modes. And upon excitation, it is ‘time’ that describes the relaxation
of an entity towards its ground state, it is ‘time’ that characterises the dephasing
of a prepared oscillator interacting with its environment (a fully isolated and, thus,
unattenuated oscillator would preserve its state indefinitely). A world free of energy
exchange would seemingly lack temporal features, as time expresses evolution of
systems which are not in a steady state and which are rich in dynamics, interactions
1 See The Book of Tao and Teh by Lao Zi, special thanks to Wei Fang (ZJU, China) from my side.
Preface
work embedded in this frame with the aim to achieve a Habilitation in physics. I
could start praising the wonderful and useful achievements that have been enabled
by the evolution of various technologies, which have utilised nanostructuring, electronics and optics together with principles from quantum mechanics, towards what
is nowadays being widely labelled as quantum technologies of the first and second
generation. But what was more important in the first place well before the beginning
of this Habilitation project, was the motivation to dig deep into the principles of
nature and to unravel concepts which may play an important role in the evolution of
our physical realm, referred to as the cosmos in the large scale and the nanocosmos
in the small scale.
Although the tools used throughout one’s life may often not bring closer to us
the furthest distant objects or events, as well as the smallest possible known length
scales or actions attributed to Max Planck’s historic studies, one can indeed shed light
on important aspects of the else hidden world through knowledge-driven actions
fed by enthusiasm and fascination. Solid-state research and particularly the work
with (semiconductor) quantum structures can add considerable knowledge in this
regard, whereas concepts and principles are tested on different, and most importantly,
accessible length scales (also time scales) and environments that not seldom mimic
with unimaginable precision those realms we are fundamentally more interested
in. Often, who studies the small, understands better the large, who explores the
large, reveals the small, and who examines both the small and large, may even
unravel details about the very small. In a physical world full of resonances (eigenstates), excitations (particles), and energy transfer (interactions), this might hold true
even more. Some reasoning from ancient philosophies and cultures might deliver
an interesting access to the building blocks and the fabric of our natural habitat,
e.g. through comparison and imagination. And with an intuition for the meaning
of the Sanskrit expression ‘Aom’ (‘Om/Aum’), perceived to be characterising the
sound of our universe, and the far-eastern ‘Tao’,
1 describing the ‘Nothingness’ and
‘Existence’ of the same origin and the endless cycles of all things in a vital flow,
quantum mechanics being governed by wave mechanics and the uncertainty principle
also lets one remember to adapt to the flow of nature and to tolerate the intangible
in the orchestra play of the universe, while striving for a deeper understanding.
Time is short to touch upon the concept of causality, its philosophical Sanskrit
counterpart ‘Karma’, and the meaningful Kramers–Kronig relations well known
from solid-state physics. By the way, what would the vivid world be like without
time? ‘Time’ manifests itself in the energy exchanges within a system governed by
interacting modes. And upon excitation, it is ‘time’ that describes the relaxation
of an entity towards its ground state, it is ‘time’ that characterises the dephasing
of a prepared oscillator interacting with its environment (a fully isolated and, thus,
unattenuated oscillator would preserve its state indefinitely). A world free of energy
exchange would seemingly lack temporal features, as time expresses evolution of
systems which are not in a steady state and which are rich in dynamics, interactions
1 See The Book of Tao and Teh by Lao Zi, special thanks to Wei Fang (ZJU, China) from my side.