We present a measurement of the 1D Lyα forest flux power spectrum, using the complete Baryon Oscillation Spectroscopic Survey (BOSS) and first extended-BOSS (eBOSS) quasars at z qso > 2.1, corresponding to the fourteenth data release (DR14) of the Sloan Digital Sky Survey (SDSS). Our results cover thirteen bins in redshift from z Lyα = 2.2 to 4.6, and scales up to k = 0.02 (km/s) −1 . From a parent sample of 180,413 visually inspected spectra, we selected the 43,751 quasars with the best quality; this data set improves the previous result from the ninth data release (DR9), both in statistical precision (achieving a reduction by a factor of two) and in redshift coverage. We also present a thorough investigation of identified sources of systematic uncertainties that affect the measurement. The resulting 1D power spectrum of this work is in excellent agreement with the one from the BOSS DR9 data.

We propose a hybrid quantum algorithm based on the Harrow-Hassidim-Lloyd (HHL) algorithm for solving a system of linear equations. In this paper, we show that our hybrid algorithm can reduce a circuit depth from the original HHL algorithm by means of a classical information feed-forward after the quantum phase estimation algorithm, and the results of the hybrid algorithm are identical to those of the HHL algorithm. In addition, it is experimentally examined with four qubits in the IBM Quantum Experience setups, and the experimental results of our algorithm show higher accurate performance on specific systems of linear equations than that of the HHL algorithm.

We consider a quantum communication task between two users Alice and Bob, in which Alice and Bob exchange their respective quantum information by means of local operations and classical communication assisted by shared entanglement. Here, we assume that Alice and Bob may have quantum side information, not transferred, and classical communication is free. In this work, we derive general upper and lower bounds for the least amount of entanglement which is necessary to perfectly perform this task, called the state exchange with quantum side information. Moreover, we show that the optimal entanglement cost can be negative when Alice and Bob make use of their quantum side information. We finally provide conditions on the initial state for the state exchange with quantum side information which give the exact optimal entanglement cost. PACS numbers: 03.67.Hk, 89.70.Cf, 03.67.Mn Introduction.-In quantum information theory, one of the most traditional research topics has been source coding problems of transmitting Alice's quantum information to Bob under various situations, with paradigmatic examples including Schumacher compression [1] and quantum teleportation [2]. A decade ago, Oppenheim and Winter devised a new type of a quantum communication task named state exchange [3] -in which Alice and Bob exchange their quantum information with each other by means of local operations and classical communication (LOCC) and shared entanglement -and they studied the least amount of entanglement consumed in the task when free classical communication is allowed.In the original state exchange task, it is assumed that both Alice and Bob do not have any quantum side information (QSI) transferrable during the protocol. On the other hand, most quantum communication tasks, including state merging [4,5] and state redistribution [6,7], begin with the assumption that either Alice or Bob has QSI. For example, in the state merging task, Bob can make use of his QSI for merging Alice's information to him, and the minimum amount of entanglement needed for merging turns out to be exactly given by the quantum conditional entropy [8] conditioned on Bob's QSI.In this work we generalize in the state exchange to an exchanging task allowing Alice's and Bob's QSI, which is called the state exchange with quantum side information.