There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

/pdf/spintronics-fundamentals-and-applications-2dx38n6phu.pdf

Spintronics: Fundamentals and applications

Conventional optical components rely on gradual phase shifts accumulated during light propagation to shape light beams. New degrees of freedom are attained by introducing abrupt phase changes over the scale of the wavelength. A two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint such phase discontinuities on propagating light as it traverses the interface between two media. Anomalous reflection and refraction phenomena are observed in this regime in optically thin arrays of metallic antennas on silicon with a linear phase variation along the interface, which are in excellent agreement with generalized laws derived from Fermat’s principle. Phase discontinuities provide great flexibility in the design of light beams, as illustrated by the generation of optical vortices through use of planar designer metallic interfaces.

http://www.zenogaburro.it/papers/LightPropagation.pdf

Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction

Strong cavity quantum electrodynamics with superconducting circuits

Qubits encoded in longlived rotational states of polar molecules interact strongly with single photons of a superconducting stripline cavity. We discuss potential applications of such a hybrid device for quantum information processing.

Polar Molecules and Circuit QED: Towards Hybrid Quantum Computing

Techniques for implementing robust quantum logic gates are provided and described. In some aspects, a quantum logic gate between a plurality of cavities comprising a first cavity and a second cavity is implemented by performing a first beam splitter operation between the first cavity and the second cavity using a coupling transmon that is dispersively coupled to both the first cavity and the second cavity, and performing a controlled phase shift operation between the second cavity and an ancilla transmon that is dispersively coupled to the second cavity but not dispersively coupled to the first cavity.

Robust quantum logical gates

Techniques for implementing a QRAM by routing quantum information through multiple modes of a bosonic system are described. According to some aspects, a single bosonic system may be configured to maintain quantum information in a large number of independent modes at the same time. Suitable operations upon these modes may allow a quantum address value to be routed to modes associated with respective bits such that the only modes altered by the operations are those associated with the addresses being accessed. These modes may be operated upon based on the stored values then extracted to obtain the desired correlated superposition of the stored bit values in the addresses. The bits stored at the address locations may be classical bits, or may be qubits.

Techniques for quantum memory addressing and related systems and methods

Amplifiers are crucial in every experiment carrying out a very sensitive measurement. However, they always degrade the information by adding noise. Quantum mechanics puts a limit on how small this degradation can be. Theoretically, the minimum noise energy added by a phase-preserving amplifier to the signal it processes amounts at least to half a photon at the signal frequency. In this article, we show that we can build a practical microwave amplifying circuit that fulfills the minimal requirements to reach this quantum limit. The readout of solid-state qubits, and more generally, the measurement of very weak signals in various areas of science, can benefit from this new superconducting device. We also discuss how our circuit can be the basic buiding block for a variety of practical applications such as frequency conversion with and without photon number gain, dynamic cooling and production of entangled signal pairs.

Robert Schoelkopf

Papers

Strong cavity quantum electrodynamics with superconducting circuits

Polar Molecules and Circuit QED: Towards Hybrid Quantum Computing

Robust quantum logical gates

Techniques for quantum memory addressing and related systems and methods

Amplifying quantum signals with Josephson tunnel junction circuits