Elementary gates for quantum computation
... quantum logic gate. As a consequence of the greater power of quantum computing as a formal system, there are many more choices for the universal gate than in classical reversible computing. In particular, DiVincenzo [28] showed that two-bit universal quantum gates are also possible; Barenco [29] ext ...
... quantum logic gate. As a consequence of the greater power of quantum computing as a formal system, there are many more choices for the universal gate than in classical reversible computing. In particular, DiVincenzo [28] showed that two-bit universal quantum gates are also possible; Barenco [29] ext ...
The Physical World as a Virtual Reality
... from invisible fields in empty space to satisfy equations about imaginary quantities. Physics stopped trying to make sense of its findings some time ago, and the effects are evident: “How unusual it is for three decades to pass without major progress in fundamental physics? Even if we look back more ...
... from invisible fields in empty space to satisfy equations about imaginary quantities. Physics stopped trying to make sense of its findings some time ago, and the effects are evident: “How unusual it is for three decades to pass without major progress in fundamental physics? Even if we look back more ...
Holographic quantum error-correcting code
... wedge C[A] supported associated withon a boundary sub-only if thin a boundary time slice ⌃. The point x lies within C[A] and thus any motion, with the boundary conditions set by the dictionary ( the causal wedge of A. reconstructed on A. On the right is a bulk time slice containing x and ⌃, that all ...
... wedge C[A] supported associated withon a boundary sub-only if thin a boundary time slice ⌃. The point x lies within C[A] and thus any motion, with the boundary conditions set by the dictionary ( the causal wedge of A. reconstructed on A. On the right is a bulk time slice containing x and ⌃, that all ...
Sharp Tunneling Peaks in a Parametric Oscillator: Quantum Resonances Missing
... It is not a sum of the kinetic and potential energy. For jj < 1, gðQ; PÞ has two symmetrically located minima, gmin ¼ ð1 þ Þ2 =4, and a saddle point, gS ¼ 0. In the presence of weak dissipation, the minima correspond to the period-2 vibrational states in the laboratory frame, which have equal amp ...
... It is not a sum of the kinetic and potential energy. For jj < 1, gðQ; PÞ has two symmetrically located minima, gmin ¼ ð1 þ Þ2 =4, and a saddle point, gS ¼ 0. In the presence of weak dissipation, the minima correspond to the period-2 vibrational states in the laboratory frame, which have equal amp ...
Chapter 3: Quantum Computing
... A method for (nearly) interaction-free measurement (IFM) specifies the design of a quantum optical sensing system that is able to determine with arbitrarily high likelihood if an obstructing body has been inserted into the system, without moving or modifying its optical components; moreover, In the ...
... A method for (nearly) interaction-free measurement (IFM) specifies the design of a quantum optical sensing system that is able to determine with arbitrarily high likelihood if an obstructing body has been inserted into the system, without moving or modifying its optical components; moreover, In the ...
Quantum States of Neutrons in the Gravitational Field
... What is gravity? In many respects this may be one of the most important questions ever asked. Answers to it have always been milestones on the way from ancient natural philosophy to modern science. Every physicist knows the legendary free fall experiments of Galileo Galilei at the dawn of empiricism ...
... What is gravity? In many respects this may be one of the most important questions ever asked. Answers to it have always been milestones on the way from ancient natural philosophy to modern science. Every physicist knows the legendary free fall experiments of Galileo Galilei at the dawn of empiricism ...
Universally valid reformulation of the Heisenberg uncertainty
... 共Received 9 October 2002; published 11 April 2003兲 The Heisenberg uncertainty principle states that the product of the noise in a position measurement and the momentum disturbance caused by that measurement should be no less than the limit set by Planck’s constant ប/2 as demonstrated by Heisenberg’s ...
... 共Received 9 October 2002; published 11 April 2003兲 The Heisenberg uncertainty principle states that the product of the noise in a position measurement and the momentum disturbance caused by that measurement should be no less than the limit set by Planck’s constant ប/2 as demonstrated by Heisenberg’s ...
Multiverse or Universe, after all
... (1997). Deutsch’s principal argument for the reality of quantum “parallel universes” is the existence of “shadow particles”, which he proposed in order to explain quantum interference phenomena in slitexperiments. But parallel universes entail heavy questions concerning identity: personal identity ( ...
... (1997). Deutsch’s principal argument for the reality of quantum “parallel universes” is the existence of “shadow particles”, which he proposed in order to explain quantum interference phenomena in slitexperiments. But parallel universes entail heavy questions concerning identity: personal identity ( ...
Chapter 6 Groups and Representations in Quantum Mechanics
... to diagonalize a Hamiltonian. Examples where this arises is the lowering of the symmetry of a system by a perturbation, where the basis functions are the eigenfunctions of the original Hamiltonian, the bonding within molecules, where the basis functions are localized around the atomic sites within t ...
... to diagonalize a Hamiltonian. Examples where this arises is the lowering of the symmetry of a system by a perturbation, where the basis functions are the eigenfunctions of the original Hamiltonian, the bonding within molecules, where the basis functions are localized around the atomic sites within t ...
Quantum computing with cavity QED
... where the coefficients are allowed to be complex numbers. It measures the amount of information, which can be stored in a two state quantum system. As an example one may think of the state of a spin 1/2 particle. Several of these qubits can be thought to form a tensor product similar as bits form by ...
... where the coefficients are allowed to be complex numbers. It measures the amount of information, which can be stored in a two state quantum system. As an example one may think of the state of a spin 1/2 particle. Several of these qubits can be thought to form a tensor product similar as bits form by ...
Quantum Computation: Theory and Implementation
... Submitted to the Department of Physics in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in Physics and to the Department of Electrical Engineering and Computer Science in Partial Fulfillment of the Requirements for the Degrees of Bachelor of Science in Electrical Engi ...
... Submitted to the Department of Physics in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in Physics and to the Department of Electrical Engineering and Computer Science in Partial Fulfillment of the Requirements for the Degrees of Bachelor of Science in Electrical Engi ...
Mathematical Aspects of Quantum Theory and Quantization Summer
... Weyl, van der Waerden, Birkhoff, and many others. Lorentz, the great Dutch physicist, was offered a chair in mathematics, simultaneosly with a chair in physics at an other Dutch university. He chose the latter and became in 1878 the first professor of theoretical physics in Europe. All this is a th ...
... Weyl, van der Waerden, Birkhoff, and many others. Lorentz, the great Dutch physicist, was offered a chair in mathematics, simultaneosly with a chair in physics at an other Dutch university. He chose the latter and became in 1878 the first professor of theoretical physics in Europe. All this is a th ...
Bose–Einstein condensation: Where many become one and so there is plenty of room at the bottom
... are merely two different states of the same underlying entity. This, of course, happens naturally in a quantum-field description where the particles are the excitations of an underlying field – just its internal movements. At a somewhat heuristic level, one can understand the quantum indistinguishab ...
... are merely two different states of the same underlying entity. This, of course, happens naturally in a quantum-field description where the particles are the excitations of an underlying field – just its internal movements. At a somewhat heuristic level, one can understand the quantum indistinguishab ...
Quantum key distribution
Quantum key distribution (QKD) uses quantum mechanics to guarantee secure communication. It enables two parties to produce a shared random secret key known only to them, which can then be used to encrypt and decrypt messages. It is often incorrectly called quantum cryptography, as it is the most well known example of the group of quantum cryptographic tasks.An important and unique property of quantum key distribution is the ability of the two communicating users to detect the presence of any third party trying to gain knowledge of the key. This results from a fundamental aspect of quantum mechanics: the process of measuring a quantum system in general disturbs the system. A third party trying to eavesdrop on the key must in some way measure it, thus introducing detectable anomalies. By using quantum superpositions or quantum entanglement and transmitting information in quantum states, a communication system can be implemented which detects eavesdropping. If the level of eavesdropping is below a certain threshold, a key can be produced that is guaranteed to be secure (i.e. the eavesdropper has no information about it), otherwise no secure key is possible and communication is aborted.The security of encryption that uses quantum key distribution relies on the foundations of quantum mechanics, in contrast to traditional public key cryptography which relies on the computational difficulty of certain mathematical functions, and cannot provide any indication of eavesdropping at any point in the communication process, or any mathematical proof as to the actual complexity of reversing the one-way functions used. QKD has provable security based on information theory, and forward secrecy.Quantum key distribution is only used to produce and distribute a key, not to transmit any message data. This key can then be used with any chosen encryption algorithm to encrypt (and decrypt) a message, which can then be transmitted over a standard communication channel. The algorithm most commonly associated with QKD is the one-time pad, as it is provably secure when used with a secret, random key. In real world situations, it is often also used with encryption using symmetric key algorithms like the Advanced Encryption Standard algorithm. In the case of QKD this comparison is based on the assumption of perfect single-photon sources and detectors, that cannot be easily implemented.