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[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

日本物理学会誌及びJournal of the Physical Society of Japanの月刊について

Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum computation. Dynamical gates have been proposed in the context of trapped ions; however, geometric phase gates (which change only the phase of the physical qubits) offer potential practical advantages because they have higher intrinsic resistance to certain small errors and might enable faster gate implementation. Here we demonstrate a universal geometric pi-phase gate between two beryllium ion-qubits, based on coherent displacements induced by an optical dipole force. The displacements depend on the internal atomic states; the motional state of the ions is unimportant provided that they remain in the regime in which the force can be considered constant over the extent of each ion's wave packet. By combining the gate with single-qubit rotations, we have prepared ions in an entangled Bell state with 97% fidelity-about six times better than in a previous experiment demonstrating a universal gate between two ion-qubits. The particular properties of the gate make it attractive for a multiplexed trap architecture that would enable scaling to large numbers of ion-qubits.

Experimental demonstration of a robust, high-fidelity geometric two ion-qubit phase gate*

Physics 1 Mr. Bigler Conservation of Momentum Unit: Momentum MA Curriculum Frameworks (2016): HS-PS2-2 MA Curriculum Frameworks (2006): 2.5 Mastery Objective(s): (Students will be able to...)  Solve problems involving collisions in which momentum is conserved, with or without an external impulse. Success Criteria:  Masses and velocities are correctly identified for each object, both before and after the collision.  Variables are correctly identified and substituted correctly into the correct part of the equation.  Algebra is correct and rounding to appropriate number of significant figures is reasonable. Tier 2 Vocabulary: momentum, collision Language Objectives:  Explain what happens before, during, and after a collision from the point of view of one of the objects participating in the collision.

Physics I.1

The quantum walk, as the quantum analog of the classical random walk, provides a feasible platform to study the topological phenomenon and nonequilibrium dynamics. Here we propose a scheme to realize the quantum walk with a single trapped ion where the Fock states provides the walk space and the zero-phonon state $|n=0\ensuremath{\rangle}$ serves as its natural boundary. Thus, our scheme offers an opportunity to investigate the dynamics of the bound states of the corresponding topological systems. In particular, the quench dynamics of the bound states can be extensively studied by tuning the bulk parameters and the local boundary operator, which are experimentally accessible. Our proposal not only offers an alternative approach to exploring the character of the bound states of the topological systems, but also offers a way to determine different phases through the dynamical processes.

Investigating the quench dynamics of the bound states in a spin-orbital-coupling system using a trapped ion

An experiment provides an important step towards understanding the relation between dynamical quantum phase transitions and the Kibble-Zurek mechanism. These results provide insight into the topological aspects of nonequilibrium dynamics.

Experimentally detecting dynamical quantum phase transitions in a slowly quenched Ising-chain model

The non-trivial zeros of the Riemann zeta function are central objects in number theory. In particular, they enable one to reproduce the prime numbers. They have also attracted the attention of physicists working in Random Matrix Theory and Quantum Chaos for decades. Here we present an experimental observation of the lowest non-trivial Riemann zeros by using a trapped ion qubit in a Paul trap, periodically driven with microwave fields. The waveform of the driving is engineered such that the dynamics of the ion is frozen when the driving parameters coincide with a zero of the real component of the zeta function. Scanning over the driving amplitude thus enables the locations of the Riemann zeros to be measured experimentally to a high degree of accuracy, providing a physical embodiment of these fascinating mathematical objects in the quantum realm.

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Riemann zeros from a periodically-driven trapped ion

We demonstrate a laser frequency stabilization method with large tuning range to stabilize a UV laser by installing piezoelectric ceramic actuators into a Fabry–Perot cavity with an ultra-low expansion spacer. To suppress piezoelectric drift, a two-layer symmetrical structure is adopted for the piezoelectric actuator, and a 14.7 GHz tuning range is achieved. The short-term drift of the piezoelectric ceramics caused by temperature and creep is eliminated, and the long-term drift is 0.268 MHz/h when the Fabry–Perot cavity is sealed in a chamber without a vacuum environment. The long-term frequency drift is mainly caused by stress release and is eliminated by compensating the cavity voltage with an open loop. Without the need for an external reference or a vacuum environment, the laser frequency stabilization system is greatly simplified, and it can be extended to wavelengths ranging from ultraviolet to infrared. Owing to its simplicity, stability, and large tuning range, it is applicable in cold atom and trapped ion experiments.

Large-tuning-range frequency stabilization of an ultraviolet laser by an open-loop piezoelectric ceramic controlled Fabry-Pérot cavity.

The invention discloses a laser frequency stabilizing device, comprises a semiconductor laser, an acoustic optical modulator, a Fabry-Perot cavity arranged in a vacuum device, a multi-channel radio frequency signal source, a combiner, a radio frequency amplifier, a photoelectric detector and a frequency mixer, wherein laser emitted by a semiconductor laser to be subjected to frequency stabilization generates +1 level or -1 level diffracted light after passing through the acousto-optic modulator for the first time, and the +1 level or -1 level diffracted light is reflected back to the acousto-optic modulator and generates +1+1 level or -1-1 level diffracted light after passing through diffraction for the second time; and the +1+1 level or -1-1 level diffracted light enters the Fabry-Perot cavity, a signal of the +1+1 level or -1-1 level diffracted light is reflected to the photoelectric detector, a detection electric signal and a demodulation signal of the multi-channel radio frequencysignal source are mixed and processed by a mixer to obtain an error signal, and the error signal is fed back to the semiconductor laser to realize frequency stabilization. According to the invention,the laser passes through the acousto-optic modulator twice to expand the frequency adjustment range, and the stability of the laser power in the frequency scanning process is further enhanced.

Ming-Zhong Ai

Papers

Investigating the quench dynamics of the bound states in a spin-orbital-coupling system using a trapped ion

Experimentally detecting dynamical quantum phase transitions in a slowly quenched Ising-chain model

Riemann zeros from a periodically-driven trapped ion

Large-tuning-range frequency stabilization of an ultraviolet laser by an open-loop piezoelectric ceramic controlled Fabry-Pérot cavity.

Laser frequency stabilizing device and method and semiconductor laser assembly adopting laser frequency stabilizing device