Preface
xiii
the achievement of many useful device platforms (sometimes in the form of quantumwell molecules and crystals), whereas quantum wires and quantum dots have their
own share in the success story of quantum devices.
When quantum entities act as an ensemble (coherently), Bose–Einstein-like
condensates (quantum fluids) of quasi-particles in matter, such as excitons and polaritons, open up a “magical realm [...] filled with fascinating phenomena and manifestations [...] [including] polariton supernovas, black and white holes as well as other
cosmological parallels such as polariton Hawking radiation” (my colleague Lorenzo
Dominici, expert on polariton fluids, phrased it once nicely for me
5 ), which to fully
comprehend I needed to be well trained in astrophysics and particle physics. In fact,
fundamental studies on exciton and exciton–polariton condensates in solids become
highly attractive when taking into account that the vacuum is considered in the literature to contain a condensate of Higgs bosons and quark condensates (leading to a
symmetry break, as the condensed system gives preference to one phase over others).
They also become highly attractive owing to mesonic condensates—possibly important for characteristics of neutron stars—being considered nuclear analogs of exciton
condensates. Given the significance of condensates, and being fascinated by related
effects such as superfluidity (and superconductivity), I am thrilled to learn more about
possibilities of how to manipulate and control the behaviour of polariton condensates—given their usefulness as optically accessible testbed—e.g. with transient
electromagnetic fields.
All this shows that a view on often intangible things from different angles can
be complementary, inspirational, and quite fulfilling, though not every single work
on a subject may excite the whole research community equally. Nevertheless, with
quantum structures and semiconductor (2D) materials one has at least various playgrounds to test physics on microscopic scales, and the study of excitations in matter
definitely provides a rich pathway to the exploration of quantum mechanics and
many-body physics. In addition, research on these systems can lead to considerable improvements in existing technologies, promising, for instance, more energyefficient, more miniaturised, and more cost-effective optoelectronic devices, ranging
from photo-transistors/solar cells to light-emitting diodes, or enabling, for example,
novel quantum-optical devices, such as single-photon sources or polariton lasers.
In the following, a selection of scientific work in this vast domain is summarised
and explained in the context of current research activities. Naturally, the discussion of
phenomena, theories, methods, and recent studies cannot be complete, and it will be
hardly possible to go into more detail within the scope of this work about these topics.
However, wherever possible and appropriate, selected representative references to
the widely available literature are provided which can deliver more insights and
explanations about the relevant matter. Thus, I am hopeful that the interested reader
can follow up on those topics through the use of these citations.
Marburg, Germany
November 2020
Arash Rahimi-Iman
5 In Polariton Physics, Springer Nature Switzerland AG, Cham, 2020.
xiii
the achievement of many useful device platforms (sometimes in the form of quantumwell molecules and crystals), whereas quantum wires and quantum dots have their
own share in the success story of quantum devices.
When quantum entities act as an ensemble (coherently), Bose–Einstein-like
condensates (quantum fluids) of quasi-particles in matter, such as excitons and polaritons, open up a “magical realm [...] filled with fascinating phenomena and manifestations [...] [including] polariton supernovas, black and white holes as well as other
cosmological parallels such as polariton Hawking radiation” (my colleague Lorenzo
Dominici, expert on polariton fluids, phrased it once nicely for me
5 ), which to fully
comprehend I needed to be well trained in astrophysics and particle physics. In fact,
fundamental studies on exciton and exciton–polariton condensates in solids become
highly attractive when taking into account that the vacuum is considered in the literature to contain a condensate of Higgs bosons and quark condensates (leading to a
symmetry break, as the condensed system gives preference to one phase over others).
They also become highly attractive owing to mesonic condensates—possibly important for characteristics of neutron stars—being considered nuclear analogs of exciton
condensates. Given the significance of condensates, and being fascinated by related
effects such as superfluidity (and superconductivity), I am thrilled to learn more about
possibilities of how to manipulate and control the behaviour of polariton condensates—given their usefulness as optically accessible testbed—e.g. with transient
electromagnetic fields.
All this shows that a view on often intangible things from different angles can
be complementary, inspirational, and quite fulfilling, though not every single work
on a subject may excite the whole research community equally. Nevertheless, with
quantum structures and semiconductor (2D) materials one has at least various playgrounds to test physics on microscopic scales, and the study of excitations in matter
definitely provides a rich pathway to the exploration of quantum mechanics and
many-body physics. In addition, research on these systems can lead to considerable improvements in existing technologies, promising, for instance, more energyefficient, more miniaturised, and more cost-effective optoelectronic devices, ranging
from photo-transistors/solar cells to light-emitting diodes, or enabling, for example,
novel quantum-optical devices, such as single-photon sources or polariton lasers.
In the following, a selection of scientific work in this vast domain is summarised
and explained in the context of current research activities. Naturally, the discussion of
phenomena, theories, methods, and recent studies cannot be complete, and it will be
hardly possible to go into more detail within the scope of this work about these topics.
However, wherever possible and appropriate, selected representative references to
the widely available literature are provided which can deliver more insights and
explanations about the relevant matter. Thus, I am hopeful that the interested reader
can follow up on those topics through the use of these citations.
Marburg, Germany
November 2020
Arash Rahimi-Iman
5 In Polariton Physics, Springer Nature Switzerland AG, Cham, 2020.