Research
- Theoretical physics
- Quantum optics
- Quantum gravity
- QFT
- QED
- Atom chips
- Decoherence phenomena
- Casimir-Polder force and QED
- Memory effects in spontaneous emission processes
- Book to appear: "Selected Problems and Solutions in Quantum Optics" collaboration with Professor Bo-Sture Skagerstam
- Logistics
- Dynamic Pricing
- Book ta appear: "Quantum Field Theory Applications in Atomic Physics and Quantum Optics" collaboration with Professor Bo-Sture K. Skagerstam
Projects
Education
- NTNU, master of science, 1992-1998
- NTNU, Ph.D., 1998-2001
- Imperial College, Post Doc, 2002-2004
- Universität Graz, Post Doc, 2005-2006
Publications
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Skagerstam, Bo-Sture & Rekdal, Per Kristian
(2026).
Fractional angular momentum and quasi-probability densities for angular degrees of freedom.
APL Quantum.
3(3).
doi:
10.1063/5.0338403.
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In the present study, we consider quasi-probability densities W[θ, p] and W1/2[θ, p] for pure states depending on two classical parameters θ and p, where −π ≤ θ ≤ π and p can take any real number. For integer values of p, the corresponding marginal distributions W[p] and W1/2[p] are positive and in accordance with Born’s rule in quantum mechanics for an angular momentum observable L. For the state ψ(θ) in Skagerstam and Rekdal [J. Opt. 26, 095201 (2024); arXiv:2312.16535v1 [quant-ph]], which can have half-integer angular momentum expectation values, negative values of W[θ, p] and W1/2[θ, p] can reveal non-classical features of ψ(θ) but in an ambiguous manner. In line with Franke-Arnold et al. [New J. Phys. 6, 103 (2004)], it is shown that experimental data of the uncertainties Δθ and ΔL can be sufficient to reveal quantum-mechanical features of such states ψ(θ) without necessarily making use of quasi-probability densities.
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Kleivenes, Ole Martin & Rekdal, Per Kristian
(2026).
Equal Opportunities at the Net: Geometric Insights Into Volleyball Scaling.
European Journal of Sport Science (EJSS).
ISSN 1746-1391.
26(6).
doi:
10.1002/ejsc.70184.
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This paper investigates how volleyball net height can be scaled to account for differences in vertical spike reach. Although suchdifferences are not exclusively determined by sex, the observed gap between male and female players makes sex‐based com-parisons particularly relevant. The official net heights of 243 cm for men and 224 cm for women differ by 19 cm, a regulationintended to compensate for physical disparities between the sexes. We examine whether this adjustment ensures comparableoffensive opportunities when evaluated in terms of observed spike reach. To isolate the geometric effect, other performance‐related factors are deliberately disregarded. Using a geometric model linking net height to spike reach, our analysis showsthat the current 19 cm gap is insufficient to ensure equal attacking opportunities. At the elite level, geometric equivalence wouldrequire lowering the women's net to about 213 cm or raising the men's net to about 253 cm. The disadvantage faced by femaleplayers becomes even more pronounced at lower performance levels.
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Skagerstam, Bo-Sture; Eriksson, Karl-Erik & Rekdal, Per Kristian
(2019).
Causality in quantum field theory with classical sources.
Journal of Physics Communications.
3(8),
p. 1–15.
doi:
10.1088/2399-6528/ab3c1c.
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In an exact quantum-mechanical framework we show that space-time expectation values of the second-quantized electromagnetic fields in the Coulomb gauge in the presence of a classical conserved source automatically lead to causal and properly retarded -independent electromagnetic field strengths. The classical -independent and gauge invariant Maxwell's equations naturally emerge in terms of quantum-mechanical expectation values and are therefore also consistent with the classical special theory of relativity. The fundamental difference between interference phenomena due to the linear nature of the classical Maxwell theory as considered in, e.g., classical optics, and interference effects of quantum states is clarified. In addition to these issues, the framework outlined also provides for a simple approach to invariance under time-reversal, some spontaneous photon emission and/or absorption processes as well as an approach to Vavilov-Čherenkov radiation. The inherent and necessary quantum uncertainty, limiting a precise space-time knowledge of expectation values of the quantum fields considered, is, finally, recalled.
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Molka-Danielsen, Judith & Rekdal, Per Kristian
(2018).
Concept and prototype design of massive open online network for innovation and knowledge sharing.
In Hogset, Heidi; Berge, Dag Magne & Dale, Karl Yngvar (Ed.),
Det regionale i det internasjonale : fjordantologien 2018.
Universitetsforlaget.
ISSN 9788215031217.
p. 82–100.
doi:
10.18261/9788215031224-2018-05.
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Small businesses in high-tech industries can be at a disadvantage when it comes to accessing research to compete within their own industries. Using a Design Science Research approach, we develop the concept of a Massive Open Online Network and implement a prototype that aims to support knowledge sharing among formal and informal persons, groups and organisations. We contribute novel knowledge in design principles and prototype that can be applied to support co-creation and innovation.
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Skagerstam, Bo-Sture; Eriksson, Karl-Erik & Rekdal, Per Kristian
(2018).
Quantum field theory with classical sources : linearized quantum gravity.
Classical and Quantum Gravity.
ISSN 0264-9381.
36(1),
p. 1–19.
doi:
10.1088/1361-6382/aaf113.
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In a previous work (Skagerstam 2018 arXiv:1801.09947v1 [quant-ph]) and in terms of an exact quantum-mechanical framework, causal and retarded expectation values of the second-quantized electro-magnetic fields in the Coulomb gauge were derived in the presence of a conserved classical electric current. The classical Maxwell’s equations then naturally emerged. In the present work, we extend these considerations to linear gravitational quantum deviations around a flat Minkowski space-time in a Coulomb-like gauge. The emergence of the classical, causal, and properly retarded linearized classical theory of general relativity with a conserved classical energy–momentum tensor is then outlined. The quantum-mechanical framework also provides for a simple approach to classical quadrupole gravitational radiation of Einstein and microscopic spontaneous graviton
emission and/or absorption processes.
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Grimsmo, Arne Løhre; Vaskinn, Asle Heide; Rekdal, Per Kristian & Skagerstam, Bo-Sture
(2013).
Memory effects in spontaneous emission processes.
Physical Review A. Atomic, Molecular, and Optical Physics (PRA).
ISSN 1050-2947.
87(2),
p. 1–12.
doi:
10.1103/PhysRevA.87.022101.
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We consider a quantum-mechanical analysis of spontaneous emission in terms of an effective two-level system with a vacuum decay rate Γ0 and transition angular frequency ωA. Our analysis is in principle exact, even though presented as a numerical solution of the time evolution including memory effects. The results so obtained are confronted with previous discussions in the literature. In terms of the dimensionless lifetime τ=tΓ0 of spontaneous emission, we obtain deviations from exponential decay of the form O(1/τ) for the decay amplitude as well as the previously obtained asymptotic behaviors of the form O(1/τ2) or O(1/τln2τ) for τ≫1. The actual asymptotic behavior depends on the adopted regularization procedure as well as on the physical parameters at hand. We show that for any reasonable range of τ and for a sufficiently large value of the required angular frequency cutoff ωc of the electromagnetic fluctuations, i.e., ωc≫ωA, one obtains either a O(1/τ) or a O(1/τ2) dependence. In the presence of physical boundaries, which can change the decay rate with many orders of magnitude, the conclusions remains the same after a suitable rescaling of parameters.
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2024).
Grunnleggende matematikk.
Pytagoras forlag.
ISBN 9788293995104.
223 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2024).
Grunnleggende matematikk : oppgaver og løsninger.
Pytagoras forlag.
ISBN 9788293995098.
130 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2024).
Innføring i bedriftsøkonomi.
Pytagoras Forlag.
ISBN 9788293995081.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2023).
Innføring i bedriftsøkonomi.
Pytagoras forlag.
ISBN 9788293995067.
182 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2023).
Anvendt statistikk : oppgaver og løsninger.
Pytagoras Forlag.
ISBN 9788293995036.
200 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2023).
Lager- og produksjonsplanlegging : oppgaver og løsninger.
Pytagoras Forlag.
ISBN 9788293995043.
183 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2022).
Anvendt statistikk.
Pytagoras forlag.
ISBN 9788269236163.
297 p.
Full text in Research Archive
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Rekdal, Per Kristian & Pettersen, Bård Inge
(2022).
Hvordan lykkes som student?
Pytagoras forlag.
ISBN 9788269236187.
90 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2022).
Diskret matematikk og informatikk : del 1.
Pytagoras forlag.
ISBN 9788269236194.
225 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2022).
Lager- og produksjonsplanlegging.
Pytagoras forlag.
ISBN 9788269236170.
188 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2021).
Anvendt statistikk : del 2: statistisk inferens.
Pytagoras forlag.
ISBN 9788269236125.
151 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2021).
Anvendt statistikk : del 1: sannsynlighetslære.
Pytagoras forlag.
ISBN 9788269236101.
198 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2021).
Anvendt matematikk.
Pytagoras forlag.
ISBN 9788269236156.
476 p.
Full text in Research Archive
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Pettersen, Bård Inge & Rekdal, Per Kristian
(2021).
Grunnleggende matematikk.
Pytagoras forlag.
ISBN 9788269236149.
138 p.
Full text in Research Archive
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Rekdal, Per Kristian; Gjeldvik, Gunnar & Lillebakk, Knut Dørum
(2024).
Samarbeider om nytt studium.
[Journal].
Romsals Budstikke Pluss.
Full text in Research Archive
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Tømte, Peder Olai; Smørdal, Magnus; Rekdal, Per Kristian; Smedhaug, Sander Nessiøy; Bakke, Oliver Bjørsnøs & Haukenes, Eirik
(2024).
Lar studentene bruke KI i matte, men ikke uten advarsler.
[TV].
tv.nrk.no.
Full text in Research Archive
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Sætren, Malene Lunde; Rekdal, Per Kristian; Pettersen, Bård Inge; Kippernes, Mari Aandahl & Eikrem, Allan
(2024).
Stadig flere studerer over nett.
[TV].
nrk.no/mr.
Full text in Research Archive
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Sætren, Malene Lunde; Rekdal, Per Kristian & Kippernes, Mari Aandahl
(2024).
Malene (34) har aldri vært på studiestedet sitt.
[Internet].
nrk.no/mr.
Full text in Research Archive
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Sætren, Malene Lunde; Rekdal, Per Kristian & Bakke, Øyvor
(2024).
Høgskolen i Molde har utviklet sitt første heldigitale studietilbud.
[TV].
NRK TV.
Full text in Research Archive
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Rekdal, Per Kristian; Vaagsether, Are & Reitan, Marie
(2022).
Kurser studenter landet rundt før studiestart.
[Journal].
Romsdals Budstikke.
Full text in Research Archive
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Svindland, Morten; Hegdal, Tone; Rekdal, Per Kristian; Haugen, Kjetil K. & Waagbø, Arild Johan
(2020).
Slik justerer faglærerere oppgavene til hjemmeeksamen.
[Journal].
Panorama.
Full text in Research Archive
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Langelo, Erik; Pettersen, Bård Inge & Rekdal, Per Kristian
(2019).
The profit-maximizing lot size problem with pricing lag effects.
Full text in Research Archive
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In 1970, Joseph Thomas extended the well-known dynamic lot size model of Wagner and Whitin to include variable prices, as well as variable production costs. This master thesis extends Thomas’ model to include something called the “lag effect”.
Formally, this master thesis models a disaggregated, finite-horizon, profit-maximizing dynamic lot size problem with pricing lag effects in demand. This effect models the tendency for customers to stock up on a product when it is offered for cheap, causing demand to increase in the “cheap” time period, while it decreases in the next. In effect, lowering the price causes demand to shift backwards in time, in addition to increasing demand as in most demand functions.
The problem is to decide in which time periods to produce, how much to produce in each period, and which price to set in each period. The objective is to maximize the total profit, defined as total revenue minus total setup cost, production cost and inventory holding cost.
Three theorems which restrict the amount of possible optimal solutions are proved. A solution is then provided to the production horizon problem, a sub-problem of the main problem. The production horizon problem is then solved with two different models: with and without the lag effect. The optimal solutions of these models are then compared for varying values of some key parameters.
Keywords: revenue management and pricing, inventory
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Langelo, Erik; Pettersen, Bård Inge & Rekdal, Per Kristian
(2019).
The profit-maximizing lot size problem with pricing lag effects.
Full text in Research Archive
Show summary
In 1970, Joseph Thomas extended the well-known dynamic lot size model
of Wagner and Whitin to include variable prices, as well as variable production
costs. This work extends Thomas’ model to include something called the lag
effect.
Formally, this work models a disaggregated, finite-horizon, profit-maximizing
dynamic lot size problem with pricing lag effects in demand. This effect models the tendency for customers to stock up on a product when it is offered for
cheap, causing demand to increase in the given time period, while it decreases
in the next. In effect, lowering the price causes demand to shift backwards in
time, in addition to increasing demand as in most demand functions.
The problem is to decide in which time periods to produce, how much to
produce in each period, and which price to set in each period. The objective
is to maximize the total profit, defined as total revenue minus total setup cost,
production cost and inventory holding cost.
Three theorems which restrict the amount of possible optimal solutions are
proved. A solution is then provided to the production horizon problem, a
sub-problem of the main problem. The production horizon problem is then
solved with two different models: with and without the lag effect. The optimal
solutions of these models are then compared for varying values of some key
parameters.
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Rekdal, Per Kristian & Hystad, Joar
(2019).
Fra tomme forelesningssaler til fulle klasserom i Molde — slik fikk de det til.
[Journal].
www.khrono.no.
Full text in Research Archive
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Rekdal, Per Kristian; Pettersen, Bård Inge & Amundsgård, Herman
(2019).
Innfører møteplikt for mattestudentene.
[Journal].
Romsdals Budstikke.
Full text in Research Archive
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Rekdal, Per Kristian; Loge, Julia & Waage, sindre
(2019).
Slik tredoblet de studentoppmøtet over natten.
[Internet].
forskerforum.no.
Full text in Research Archive
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Bjerkeland, Øystein & Rekdal, Per Kristian
(2016).
Stort stryk på matte-eksamen.
[Journal].
Romsdals budstikke.
Full text in Research Archive
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30 prosent av studentene som tok eksamen ved Høgskolen i Molde før jul fikk strykkarakteren F i matematikk. I Kristiansund strøk halvparten av studentene.
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Rekdal, Per Kristian & Resvoll, Liv-Inger
(2016).
Digitalisering viktig for studentrekrutteringa.
[Internet].
norgesuniversitetet.no.
Full text in Research Archive
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Rekdal, Per Kristian; Nordhaug, Hans Fredrik & Waagbø, Arild Johan
(2016).
Gulltilbud i matematikk for fjernstudenter.
[Journal].
http://panorama.himolde.no.
Full text in Research Archive
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Rekdal, Per Kristian; Holme, Svein Ludvik & Waagbø, Arild Johan
(2016).
Studenter krever mer undervisning på video.
[Journal].
http://panorama.himolde.no.
Full text in Research Archive
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Silseth, Ingvild & Rekdal, Per Kristian
(2016).
Foreleser ved Høgskolen i Molde kan bli «årets formidler» : Per Kristian Rekdal er en av 39 finalister i Morgenbladets kåring.
[Journal].
Romsdals budstikke.
Full text in Research Archive
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Rekdal, Per Kristian; Bjerknes, Silje Steinnes; Ellingseter, Tore & Wisborg, Esben Blix
(2015).
På noregstoppen i fjernundervisning.
[TV].
www.nrk.no.
Full text in Research Archive
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Rekdal, Per Kristian; Haugen, Kjetil K. & Waagbø, Arild Johan
(2015).
X-erne ses av 2-300 studenter daglig.
[Journal].
http://panorama.himolde.no.
Full text in Research Archive
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Rekdal, Per Kristian & Hagesæther, Pål Vegard
(2014).
En flom av norske nettilbud : Høgskolen i Molde er blant pionerene i Norge.
[Journal].
Aftenposten.
Full text in Research Archive
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Waagbø, Arild Johan; Skagerstam, Bo-Sture & Rekdal, Per Kristian
(2014).
Kvantefysikere har sett lyset.
[Journal].
http://panorama.himolde.no.
Full text in Research Archive
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Waagbø, Arild Johan; Skagerstam, Bo-Sture & Rekdal, Per Kristian
(2014).
Vil tilby forskningen sin gratis på internett.
[Journal].
Khrono.no.
Full text in Research Archive
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Rekdal, Per Kristian & Landsvik, Solveig Oterhals
(2014).
Høgskolen utvider radiusen.
[Journal].
Romsdals budstikke.
Full text in Research Archive
Show summary
Studenter fra hele landet følger undervisning på video. 29 fag tilgjengelig. Bruker Facebook til fjernveiledning
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Rekdal, Per Kristian & Waagbø, Arild Johan
(2014).
Facebook har størst gjennomslagskraft.
[Journal].
http:\\panorama.himolde.no.
Full text in Research Archive
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Rekdal, Per Kristian & Hagesæther, Pål Vegard
(2014).
Harvard i spissen for utdanningsrevolusjon : flom av nye norske nettilbud.
[Journal].
Aftenposten.
Full text in Research Archive
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Slåtto, Torhild & Rekdal, Per Kristian
(2013).
Helt åpne læringsressurser fra Høgskolen i Molde : klasseromsfølelsen skal med inn på nettet.
[Internet].
Synkron : magasin for innovativ utdanning, 2013 nr 3.
Full text in Research Archive
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Mens mooc-feberen slår inn på de nordiske universitetene, jobber Høgskolen i Molde etter en annen idé. Utdanning skal ut til folket, det vil si til dem som ikke kan komme til campus. Det skal være gratis for studenten, og det skal ikke koste for mye for høgskolen heller
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Published Sep. 3, 2018 4:00 PM
- Last modified Apr. 11, 2026 6:49 PM