Dual-path source engineering in integrated quantum optics
... these offer high flexibility in the spatial domain [12], the low brightness compared to their waveguide counterparts [13], as well as possible losses and instabilities in the bulk-waveguide interface, prevents the scaling to many photons coupled to many inputs of a linear network. Waveguide sources ...
... these offer high flexibility in the spatial domain [12], the low brightness compared to their waveguide counterparts [13], as well as possible losses and instabilities in the bulk-waveguide interface, prevents the scaling to many photons coupled to many inputs of a linear network. Waveguide sources ...
Why the brain is probably not a quantum computer Max Tegmark
... independent, with the density matrix of the separable form q q1 q2 . If the subsystems start out independent, any interaction will at least initially increase the subsystem entropies Si , thereby increasing the mutual information, since the entropy S of the total system always remains constant. ...
... independent, with the density matrix of the separable form q q1 q2 . If the subsystems start out independent, any interaction will at least initially increase the subsystem entropies Si , thereby increasing the mutual information, since the entropy S of the total system always remains constant. ...
Wick calculus
... steps toward addressing this question and how the Wick transform has been put to work in this regard. The paper is organized as follows: We will use the harmonic oscillator to exhibit the connection between Wickordered polynomials and the familiar Hermite polynomials. Then we turn to Wick transforms ...
... steps toward addressing this question and how the Wick transform has been put to work in this regard. The paper is organized as follows: We will use the harmonic oscillator to exhibit the connection between Wickordered polynomials and the familiar Hermite polynomials. Then we turn to Wick transforms ...
Gate-defined quantum confinement in suspended bilayer graphene
... pair of top gates. Furthermore, an even–odd effect is visible in a Coulomb blockade plot as a function of Vt12 at fixed Vt34 = 9.27 V and Vb = − 10.7 V (Supplementary Fig. S5), consistent with the presence of a twofold degeneracy. The conductance modulations that couple exclusively to the back gate ...
... pair of top gates. Furthermore, an even–odd effect is visible in a Coulomb blockade plot as a function of Vt12 at fixed Vt34 = 9.27 V and Vb = − 10.7 V (Supplementary Fig. S5), consistent with the presence of a twofold degeneracy. The conductance modulations that couple exclusively to the back gate ...
Relaxation dynamics of a quantum Brownian particle in an ideal gas
... instance of the fluctuation-dissipation theorem. An issue of much debate is the fact that the Caldeira-Leggett master equation is not of Lindblad-form and therefore does not preserve the positivity of some initial states. As is well known [9], this can be healed by adding a “position-diffusion” term p ...
... instance of the fluctuation-dissipation theorem. An issue of much debate is the fact that the Caldeira-Leggett master equation is not of Lindblad-form and therefore does not preserve the positivity of some initial states. As is well known [9], this can be healed by adding a “position-diffusion” term p ...
Fundamental Mathematics of Consciousness
... Recursion; Creative interactivity; Contextuality; Gödel’s Theorem; Adjoint; Commutation; Space; Time ...
... Recursion; Creative interactivity; Contextuality; Gödel’s Theorem; Adjoint; Commutation; Space; Time ...
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.