Macroscopic quantum state analyzed particle by particle.
نویسندگان
چکیده
Macroscopic quantum phenomena, e.g., superconductivity and squeezing, are believed to result from entanglement of macroscopic numbers of particles. We report the first direct study of this kind of entanglement: we use discrete quantum tomography to reconstruct the joint quantum state of photon pairs extracted from polarization-squeezed light. Our observations confirm several predictions from spin-squeezing theory [Beduini et al., Phys. Rev. Lett. 111, 143601 (2013)], including strong entanglement and entanglement of all photon pairs within the squeezing coherence time. This photon-by-photon analysis may give insight into other macroscopic many-body systems, e.g., photon Bose-Einstein condensates.
منابع مشابه
Spontaneous Symmetry Breaking, Off-diagonal Long-range Order, and Nucleation of Quantum State
Spontaneous symmetry breaking is determined by quantum mechanical measurement, and is classified to two types according to whether Hamiltonian commutes the relevant observable, the average of which is the order parameter. A supplement regarding phases is given to the expansion postulate and validate ensemble description of many-particle systems. Interference between many-particle states, macros...
متن کاملQuantum Computation with Bose-Einstein Condensates
It is proposed that quantum computation can be implemented on the basis of macroscopic quantum coherence of a many-particle system, especially the Bose-Einstein condensates, instead of a pure state. Moreover, since a macroscopic condensate “wavefunction” is described by a nonlinear Schrödinger equation, and the nonlinearity is tunable, one may be able to build a quantum computer composed of bot...
متن کاملKl-th 96/6 Application of Instantons: Quenching of Macroscopic Quantum Coherence and Macroscopic Fermi–particle Configurations
Starting from the coherent state representation of the evolution operator with the help of the path–integral, we derive a formula for the low–lying levels E = ǫ0 − 2△ǫ cos(s+ ξ)π of a quantum spin system. The quenching of macroscopic quantum coherence is understood as the vanishing of cos(s+ ξ)π in disagreement with the suppression of tunneling (i.e. △ǫ = 0) as claimed in the literature. A new ...
متن کاملImpact of the Existence of One-Way Functionson the Conceptual Difficulties of Quantum Measurements
One-way functions are functions that are easy to compute but hard to invert. Their existence is an open conjecture; it would imply the existence of intractable problems (i.e. NP-problems which are not in the P complexity class). If true, the existence of one-way functions would have an impact on the theoretical framework of physics, in particularly, quantum mechanics. Such aspect of one-way fun...
متن کاملDecoherence effects on quantum Fisher information of multi-qubit W states
Quantum fisher information of a parameter characterizing the sensitivity of a state with respect to parameter changes. In this paper, we study the quantum fisher information of the W state for four, five, six and seven particles in decoherence channels, such as amplitude damping, phase damping and depolarizing channel. Using Krauss operators for decoherence channels components, we investigate t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 114 12 شماره
صفحات -
تاریخ انتشار 2015