Today`s class: Schrödinger`s Cat Paradox
... that’s both dead and alive at the same time. • Schrodinger illustrated a problem with QM: it predicts that cat will be in a superposition state UNTIL WE MEASURE IT, but doesn’t define what it means to make a measurement. In fact, a measurement is any interaction with the environment – intentional o ...
... that’s both dead and alive at the same time. • Schrodinger illustrated a problem with QM: it predicts that cat will be in a superposition state UNTIL WE MEASURE IT, but doesn’t define what it means to make a measurement. In fact, a measurement is any interaction with the environment – intentional o ...
Strong no-go theorem for Gaussian quantum bit commitment
... two mistrustful parties: Alice must commit to a certain bit, which should remain hidden to Bob until she reveals its value. A traditional picture for this protocol is as follows: Alice locks a secret bit into a safe that she gives to Bob; then, when she wants to reveal her secret, she simply hands o ...
... two mistrustful parties: Alice must commit to a certain bit, which should remain hidden to Bob until she reveals its value. A traditional picture for this protocol is as follows: Alice locks a secret bit into a safe that she gives to Bob; then, when she wants to reveal her secret, she simply hands o ...
Resource Letter SPE-1: Single-Photon Experiments in the Undergraduate Laboratory
... these experiments work well, not hinging on a specific physical condition that is hard to meet. They provide conclusive results that will stimulate undergraduates. Section V provides references to original landmark experiments that inspired the undergraduate adaptations described above. Quite often, ...
... these experiments work well, not hinging on a specific physical condition that is hard to meet. They provide conclusive results that will stimulate undergraduates. Section V provides references to original landmark experiments that inspired the undergraduate adaptations described above. Quite often, ...
Incoherent pair background processes with full polarizations at the ILC
... to a miniumum by writing new analytic expressions in forms similar to those already existing in CAIN. The monte carlo scheme that determines whether a particular pair production process will take place relies on the BreitWheeler cross-section structure with respect to final electron energy and momen ...
... to a miniumum by writing new analytic expressions in forms similar to those already existing in CAIN. The monte carlo scheme that determines whether a particular pair production process will take place relies on the BreitWheeler cross-section structure with respect to final electron energy and momen ...
Majorana and the path-integral approach to Quantum Mechanics
... integration paths. In fact, the different initial conditions are, in any case, always referred to the same initial time (ta ), while the determined quantum state corresponds to a fixed end time (tb ). The introduced issue of “slightly different classical motions” (the emphasis is given by Majorana h ...
... integration paths. In fact, the different initial conditions are, in any case, always referred to the same initial time (ta ), while the determined quantum state corresponds to a fixed end time (tb ). The introduced issue of “slightly different classical motions” (the emphasis is given by Majorana h ...
Towards Fully Quantum Mechanical 3D Device Simulations
... quantum mechanically according to Eq. (1) with selfconsistently computed local Fermi levels rather than semiclassically. Our current density of 3.6 ×104 A/cm2 compares well with the PME result of 6.8 ×104 A/cm2 . However, we note that the current is directly proportional to the mobility in our model ...
... quantum mechanically according to Eq. (1) with selfconsistently computed local Fermi levels rather than semiclassically. Our current density of 3.6 ×104 A/cm2 compares well with the PME result of 6.8 ×104 A/cm2 . However, we note that the current is directly proportional to the mobility in our model ...
Comment on "Spin-Gradient-Driven Light Amplification in a Quantum Plasma"
... a small perturbation [of O(µB B/T ) ≪ 1] to the standard Vlasov kinetics (as also stated in [2]). At high temperatures, Larmor moments µL = T /B dominate over spin moments (µL ≫ µB ). Also, at any T , the quantum spin force µB ∇B is a very small perturbation to the classical orbit theory based on th ...
... a small perturbation [of O(µB B/T ) ≪ 1] to the standard Vlasov kinetics (as also stated in [2]). At high temperatures, Larmor moments µL = T /B dominate over spin moments (µL ≫ µB ). Also, at any T , the quantum spin force µB ∇B is a very small perturbation to the classical orbit theory based on th ...
Violation of the Schiff theorem for unstable atomic - Plasma-Gate
... In conclusion we formulate the results of the present work. The Schiff theorem (screening of an external static homogeneous electric field on the nucleus of a neutral atom) is violated for the excited (unstable) atomic states. As a matter of principle this violation cannot be observed in the scatter ...
... In conclusion we formulate the results of the present work. The Schiff theorem (screening of an external static homogeneous electric field on the nucleus of a neutral atom) is violated for the excited (unstable) atomic states. As a matter of principle this violation cannot be observed in the scatter ...
http://math.ucsd.edu/~nwallach/venice.pdf
... by this tensor product. Now, the Hamiltonian HU will not preserve the tensor product structure. Thus, even though we are attempting to do only operations on states in V the environment will cause the states to change in ways that are beyond the control of the experiment that we might be attempting t ...
... by this tensor product. Now, the Hamiltonian HU will not preserve the tensor product structure. Thus, even though we are attempting to do only operations on states in V the environment will cause the states to change in ways that are beyond the control of the experiment that we might be attempting t ...
probability in quantum mechanics
... from which the latter can be deduced exactly, the long-standing problem of how quantum mechanics is related to stochastic processes is studied. ...
... from which the latter can be deduced exactly, the long-standing problem of how quantum mechanics is related to stochastic processes is studied. ...
An Improved Quantum Algorithm for Searching an Ordered List
... from (29), ensuring that the pairs of coefficients a,r and a,N −r , and b,r and b,N −r , are each treated as a single variable to respect the symmetries in (20) and (21). Once we have found the gradient, we reduce the problem to a one-dimensional search along this vector to find a new C for which ...
... from (29), ensuring that the pairs of coefficients a,r and a,N −r , and b,r and b,N −r , are each treated as a single variable to respect the symmetries in (20) and (21). Once we have found the gradient, we reduce the problem to a one-dimensional search along this vector to find a new C for which ...
Transition amplitudes versus transition probabilities and a
... Formulae (15.5) and (15.6) show clearly that in the classical limit, when ;,,~ 0, the two copies of space-time collapse into one, and only one trajectory, namely the one that is determined by the Newton equations, contributes to the transition probability. The same concept of a reduplicated space-ti ...
... Formulae (15.5) and (15.6) show clearly that in the classical limit, when ;,,~ 0, the two copies of space-time collapse into one, and only one trajectory, namely the one that is determined by the Newton equations, contributes to the transition probability. The same concept of a reduplicated space-ti ...
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.