Next Issue
Volume 3, June
Previous Issue
Volume 2, December

Quantum Rep., Volume 3, Issue 1 (March 2021) – 14 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Order results
Result details
Select all
Export citation of selected articles as:
Article
What Is Rational and Irrational in Human Decision Making
Quantum Rep. 2021, 3(1), 242-252; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010014 - 19 Mar 2021
Cited by 1 | Viewed by 928
Abstract
There has been a growing trend to develop cognitive models based on the mathematics of quantum theory. A common theme in the motivation of such models has been findings which apparently challenge the applicability of classical formalisms, specifically ones based on classical probability [...] Read more.
There has been a growing trend to develop cognitive models based on the mathematics of quantum theory. A common theme in the motivation of such models has been findings which apparently challenge the applicability of classical formalisms, specifically ones based on classical probability theory. Classical probability theory has had a singularly important place in cognitive theory, because of its (in general) descriptive success but, more importantly, because in decision situations with low, equivalent stakes it offers a multiply justified normative standard. Quantum cognitive models have had a degree of descriptive success and proponents of such models have argued that they reveal new intuitions or insights regarding decisions in uncertain situations. However, can quantum cognitive models further benefit from normative justifications analogous to those for classical probability models? If the answer is yes, how can we determine the rational status of a decision, which may be consistent with quantum theory, but inconsistent with classical probability theory? In this paper, we review the proposal from Pothos, Busemeyer, Shiffrin, and Yearsley (2017), that quantum decision models benefit from normative justification based on the Dutch Book Theorem, in exactly the same way as models based on classical probability theory. Full article
Show Figures

Figure 1

Article
Remote State Design for Efficient Quantum Metrology with Separable and Non-Teleporting States
Quantum Rep. 2021, 3(1), 228-241; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010013 - 09 Mar 2021
Viewed by 820
Abstract
Measurements leading to the collapse of states and the non-local quantum correlations are the key to all applications of quantum mechanics as well as in the studies of quantum foundation. The former is crucial for quantum parameter estimation, which is greatly affected by [...] Read more.
Measurements leading to the collapse of states and the non-local quantum correlations are the key to all applications of quantum mechanics as well as in the studies of quantum foundation. The former is crucial for quantum parameter estimation, which is greatly affected by the physical environment and the measurement scheme itself. Its quantification is necessary to find efficient measurement schemes and circumvent the non-desirable environmental effects. This has led to the intense investigation of quantum metrology, extending the Cramér–Rao bound to the quantum domain through quantum Fisher information. Among all quantum states, the separable ones have the least quantumness; being devoid of the fragile non-local correlations, the component states remain unaffected in local operations performed by any of the parties. Therefore, using these states for the remote design of quantum states with high quantum Fisher information can have diverse applications in quantum information processing; accurate parameter estimation being a prominent example, as the quantum information extraction solely depends on it. Here, we demonstrate that these separable states with the least quantumness can be made extremely useful in parameter estimation tasks, and further show even in the case of the shared channel inflicted with the amplitude damping noise and phase flip noise, there is a gain in Quantum Fisher information (QFI). We subsequently pointed out that the symmetric W states, incapable of perfectly teleporting an unknown quantum state, are highly effective for remotely designing quantum states with high quantum Fisher information. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
How Does the Planck Scale Affect Qubits?
Quantum Rep. 2021, 3(1), 196-227; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010012 - 01 Mar 2021
Viewed by 754
Abstract
Gedanken experiments in quantum gravity motivate generalised uncertainty relations (GURs) implying deviations from the standard quantum statistics close to the Planck scale. These deviations have been extensively investigated for the non-spin part of the wave function, but existing models tacitly assume that spin [...] Read more.
Gedanken experiments in quantum gravity motivate generalised uncertainty relations (GURs) implying deviations from the standard quantum statistics close to the Planck scale. These deviations have been extensively investigated for the non-spin part of the wave function, but existing models tacitly assume that spin states remain unaffected by the quantisation of the background in which the quantum matter propagates. Here, we explore a new model of nonlocal geometry in which the Planck-scale smearing of classical points generates GURs for angular momentum. These, in turn, imply an analogous generalisation of the spin uncertainty relations. The new relations correspond to a novel representation of SU(2) that acts nontrivially on both subspaces of the composite state describing matter-geometry interactions. For single particles, each spin matrix has four independent eigenvectors, corresponding to two 2-fold degenerate eigenvalues ħ±(ħ+β)/2, where β is a small correction to the effective Planck’s constant. These represent the spin states of a quantum particle immersed in a quantum background geometry and the correction by β emerges as a direct result of the interaction terms. In addition to the canonical qubits states, |0=| and |1=|, there exist two new eigenstates in which the spin of the particle becomes entangled with the spin sector of the fluctuating spacetime. We explore ways to empirically distinguish the resulting "geometric" qubits, |0 and |1, from their canonical counterparts. Full article
(This article belongs to the Special Issue Relevance of Information Geometry in Quantum Information Science)
Article
Effective and Efficient Resonant Transitions in Periodically Modulated Quantum Systems
Quantum Rep. 2021, 3(1), 173-195; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010011 - 27 Feb 2021
Cited by 1 | Viewed by 663
Abstract
We analyze periodically modulated quantum systems with SU(2) and SU(1,1) symmetries. Transforming the Hamiltonian into the Floquet representation we apply the Lie transformation method, which allows us to classify all effective resonant transitions emerging in time-dependent systems. In the case of a single periodically perturbed system, we propose an explicit iterative procedure for the determination of the effective interaction constants corresponding to every resonance both for weak and strong modulation. For coupled quantum systems we determine the efficient resonant transitions appearing as a result of time modulation and intrinsic non-linearities. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
Spectral Explanation for Statistical Odd-Even Staggering in Few Fermions Systems
Quantum Rep. 2021, 3(1), 166-172; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010010 - 16 Feb 2021
Cited by 1 | Viewed by 659
Abstract
Odd-even statistical staggering in a Lipkin-like few fermions model has been recently encountered. Of course, staggering in nuclear binding energies is a well established fact. Similar effects are detected in other finite fermion systems as well, as for example, ultra small metallic grains [...] Read more.
Odd-even statistical staggering in a Lipkin-like few fermions model has been recently encountered. Of course, staggering in nuclear binding energies is a well established fact. Similar effects are detected in other finite fermion systems as well, as for example, ultra small metallic grains and metal clusters. We work in this effort with the above-mentioned Lipkin-like, two-level fermion model and show that statistical staggering effects can be detailedly explained by recourse to a straightforward analysis of the associated energy-spectra. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
Topological Quantum Computing and 3-Manifolds
Quantum Rep. 2021, 3(1), 153-165; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010009 - 05 Feb 2021
Viewed by 931
Abstract
In this paper, we will present some ideas to use 3D topology for quantum computing. Topological quantum computing in the usual sense works with an encoding of information as knotted quantum states of topological phases of matter, thus being locked into topology to [...] Read more.
In this paper, we will present some ideas to use 3D topology for quantum computing. Topological quantum computing in the usual sense works with an encoding of information as knotted quantum states of topological phases of matter, thus being locked into topology to prevent decay. Today, the basic structure is a 2D system to realize anyons with braiding operations. From the topological point of view, we have to deal with surface topology. However, usual materials are 3D objects. Possible topologies for these objects can be more complex than surfaces. From the topological point of view, Thurston’s geometrization theorem gives the main description of 3-dimensional manifolds. Here, complements of knots do play a prominent role and are in principle the main parts to understand 3-manifold topology. For that purpose, we will construct a quantum system on the complements of a knot in the 3-sphere. The whole system depends strongly on the topology of this complement, which is determined by non-contractible, closed curves. Every curve gives a contribution to the quantum states by a phase (Berry phase). Therefore, the quantum states can be manipulated by using the knot group (fundamental group of the knot complement). The universality of these operations was already showed by M. Planat et al. Full article
(This article belongs to the Special Issue Groups, Geometry and Topology for Quantum Computations)
Show Figures

Figure 1

Article
Hybrid Quantum-Classical Eigensolver without Variation or Parametric Gates
Quantum Rep. 2021, 3(1), 137-152; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010008 - 31 Jan 2021
Cited by 1 | Viewed by 880
Abstract
The use of near-term quantum devices that lack quantum error correction, for addressing quantum chemistry and physics problems, requires hybrid quantum-classical algorithms and techniques. Here, we present a process for obtaining the eigenenergy spectrum of electronic quantum systems. This is achieved by projecting [...] Read more.
The use of near-term quantum devices that lack quantum error correction, for addressing quantum chemistry and physics problems, requires hybrid quantum-classical algorithms and techniques. Here, we present a process for obtaining the eigenenergy spectrum of electronic quantum systems. This is achieved by projecting the Hamiltonian of a quantum system onto a limited effective Hilbert space specified by a set of computational bases. From this projection, an effective Hamiltonian is obtained. Furthermore, a process for preparing short depth quantum circuits to measure the corresponding diagonal and off-diagonal terms of the effective Hamiltonian is given, whereby quantum entanglement and ancilla qubits are used. The effective Hamiltonian is then diagonalized on a classical computer using numerical algorithms to obtain the eigenvalues. The use case of this approach is demonstrated for ground state and excited states of BeH2 and LiH molecules, and the density of states, which agrees well with exact solutions. Additionally, hardware demonstration is presented using IBM quantum devices for H2 molecule. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Review
Exploiting the Fruitfly, Drosophila melanogaster, to Identify the Molecular Basis of Cryptochrome-Dependent Magnetosensitivity
Quantum Rep. 2021, 3(1), 127-136; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010007 - 27 Jan 2021
Viewed by 1099
Abstract
The flavoprotein CRYPTOCHROME (CRY) is now generally believed to be a magnetosensor, providing geomagnetic information via a quantum effect on a light-initiated radical pair reaction. Whilst there is considerable physical and behavioural data to support this view, the precise molecular basis of animal [...] Read more.
The flavoprotein CRYPTOCHROME (CRY) is now generally believed to be a magnetosensor, providing geomagnetic information via a quantum effect on a light-initiated radical pair reaction. Whilst there is considerable physical and behavioural data to support this view, the precise molecular basis of animal magnetosensitivity remains frustratingly unknown. A key reason for this is the difficulty in combining molecular and behavioural biological experiments with the sciences of magnetics and spin chemistry. In this review, we highlight work that has utilised the fruit fly, Drosophila melanogaster, which provides a highly tractable genetic model system that offers many advantages for the study of magnetosensitivity. Using this “living test-tube”, significant progress has been made in elucidating the molecular basis of CRY-dependent magnetosensitivity. Full article
(This article belongs to the Special Issue Recent Advances in Quantum Biology)
Show Figures

Figure 1

Review
Quantum Biology: An Update and Perspective
Quantum Rep. 2021, 3(1), 80-126; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010006 - 26 Jan 2021
Cited by 6 | Viewed by 3999
Abstract
Understanding the rules of life is one of the most important scientific endeavours and has revolutionised both biology and biotechnology. Remarkable advances in observation techniques allow us to investigate a broad range of complex and dynamic biological processes in which living systems could [...] Read more.
Understanding the rules of life is one of the most important scientific endeavours and has revolutionised both biology and biotechnology. Remarkable advances in observation techniques allow us to investigate a broad range of complex and dynamic biological processes in which living systems could exploit quantum behaviour to enhance and regulate biological functions. Recent evidence suggests that these non-trivial quantum mechanical effects may play a crucial role in maintaining the non-equilibrium state of biomolecular systems. Quantum biology is the study of such quantum aspects of living systems. In this review, we summarise the latest progress in quantum biology, including the areas of enzyme-catalysed reactions, photosynthesis, spin-dependent reactions, DNA, fluorescent proteins, and ion channels. Many of these results are expected to be fundamental building blocks towards understanding the rules of life. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
Finite Groups for the Kummer Surface: The Genetic Code and a Quantum Gravity Analogy
Quantum Rep. 2021, 3(1), 68-79; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010005 - 25 Jan 2021
Cited by 1 | Viewed by 928
Abstract
The Kummer surface was constructed in 1864. It corresponds to the desingularization of the quotient of a 4-torus by 16 complex double points. Kummer surface is known to play a role in some models of quantum gravity. Following our recent model of the [...] Read more.
The Kummer surface was constructed in 1864. It corresponds to the desingularization of the quotient of a 4-torus by 16 complex double points. Kummer surface is known to play a role in some models of quantum gravity. Following our recent model of the DNA genetic code based on the irreducible characters of the finite group G5:=(240,105)Z52O (with 2O the binary octahedral group), we now find that groups G6:=(288,69)Z62O and G7:=(336,118)Z72O can be used as models of the symmetries in hexamer and heptamer proteins playing a vital role for some biological functions. Groups G6 and G7 are found to involve the Kummer surface in the structure of their character table. An analogy between quantum gravity and DNA/RNA packings is suggested. Full article
(This article belongs to the Special Issue Groups, Geometry and Topology for Quantum Computations)
Show Figures

Figure 1

Article
How to Erase Quantum Monogamy?
Quantum Rep. 2021, 3(1), 53-67; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010004 - 21 Jan 2021
Viewed by 940
Abstract
The phenomenon of quantum erasure exposed a remarkable ambiguity in the interpretation of quantum entanglement. On the one hand, the data is compatible with the possibility of arrow-of-time violations. On the other hand, it is also possible that temporal non-locality is an artifact [...] Read more.
The phenomenon of quantum erasure exposed a remarkable ambiguity in the interpretation of quantum entanglement. On the one hand, the data is compatible with the possibility of arrow-of-time violations. On the other hand, it is also possible that temporal non-locality is an artifact of post-selection. Twenty years later, this problem can be solved with a quantum monogamy experiment, in which four entangled quanta are measured in a delayed-choice arrangement. If Bell violations can be recovered from a “monogamous” quantum system, then the arrow of time is obeyed at the quantum level. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
Superradiance in Quantum Vacuum
Quantum Rep. 2021, 3(1), 42-52; https://doi.org/10.3390/quantum3010003 - 03 Jan 2021
Viewed by 985
Abstract
A new process associated with the nonlinear optical properties of the electromagnetic quantum vacuum is described. It corresponds to the superradiant emission of photons, resulting from the interaction of an intense laser pulse with frequency ω0 with a counter-propagating high-harmonic signal with a spectrum of frequencies nω1, for n integer, in the absence of matter. Under certain conditions, photon emission from vacuum will be enhanced by the square of the number of intense spikes associated with the high-harmonic pulse. This occurs when the field created by the successive spikes is coherently emitted, as in typical superradiant processes involving atoms. Subradiant conditions, where the nonlinearity of quantum vacuum is entirely suppressed, can equally be defined. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
Spacetime Paths as a Whole
Quantum Rep. 2021, 3(1), 13-41; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010002 - 31 Dec 2020
Viewed by 1637
Abstract
The mathematical similarities between non-relativistic wavefunction propagation in quantum mechanics and image propagation in scalar diffraction theory are used to develop a novel understanding of time and paths through spacetime as a whole. It is well known that Feynman’s original derivation of the [...] Read more.
The mathematical similarities between non-relativistic wavefunction propagation in quantum mechanics and image propagation in scalar diffraction theory are used to develop a novel understanding of time and paths through spacetime as a whole. It is well known that Feynman’s original derivation of the path integral formulation of non-relativistic quantum mechanics uses time-slicing to calculate amplitudes as sums over all possible paths through space, but along a definite curve through time. Here, a 3+1D spacetime wave distribution and its 4-momentum dual are formally developed which have no external time parameter and therefore cannot change or evolve in the usual sense. Time is thus seen “from the outside”. A given 3+1D momentum representation of a system encodes complete dynamical information, describing the system’s spacetime behavior as a whole. A comparison is made to the mathematics of holograms, and properties of motion for simple systems are derived. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Article
Tunable Topological Beam Splitter in Superconducting Circuit Lattice
Quantum Rep. 2021, 3(1), 1-12; https://0-doi-org.brum.beds.ac.uk/10.3390/quantum3010001 - 25 Dec 2020
Cited by 1 | Viewed by 993
Abstract
In the usual Su–Schrieffer–Heeger (SSH) model with an even number of lattice sites, the topological pumping between left and right edge states cannot be easily realized since the edge states occupy two-end sites simultaneously. Here we propose a scheme to investigate the topological [...] Read more.
In the usual Su–Schrieffer–Heeger (SSH) model with an even number of lattice sites, the topological pumping between left and right edge states cannot be easily realized since the edge states occupy two-end sites simultaneously. Here we propose a scheme to investigate the topological edge pumping in an even-sized periodically modulated SSH model mapped by a one dimensional superconducting transmission line resonators array. We find that the photon initially prepared in the first resonator can be finally observed at the two-end resonators with a certain proportion. The final photon splitting at the two-end resonators indicates that the present superconducting circuit is expected to realize the topological beam splitter. Further, we demonstrate that the splitting proportion between the two-end resonators can be arbitrarily tuned from 1 to 0, implying the potential feasibility of implementing the tunable topological beam splitter. Meanwhile, we also show that the tunable topological beam splitter is immune to the mild disorder added into the system due to the topology protection of the zero energy modes, and find that the tunable topological beam splitter is much more robust to the global on-site disorder compared with the nearest neighbor disorder. Our work greatly extends the practical application of topological matter in quantum information processing and opens up a new way towards the engineering of topological quantum optical device. Full article
(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop