arXiv subjects

Neal C. Pisenti

Publications and source records attributed to Neal C. Pisenti.

4 recordsLinked to original sources

arXiv2020

Generalized Hamiltonian to describe imperfections in ion-light interaction

We derive a general Hamiltonian that governs the interaction between an $N$-ion chain and an externally controlled laser field, where the ion motion is quantized and the laser field is considered beyond the plane-wave approximation. This general form not only explicitly includes terms that are used to drive ion-ion entanglement, but also a series of unwanted terms that can lead to quantum gate infidelity. We demonstrate the power of our expressivity of the general Hamiltonian by singling out the effect of axial mode heating and confirm this experimentally. We discuss pathways forward in furthering the trapped-ion quantum computational quality, guiding hardware design decisions.

quant-ph↗

arXiv2019

Isotope-shift spectroscopy of the ${^1}S_0 \rightarrow {^3}P_1$ and ${^1}S_0 \rightarrow {^3}P_0$ transitions in strontium

Isotope shift spectroscopy with narrow optical transitions provides a benchmark for atomic structure calculations and has also been proposed as a way to constrain theories predicting physics beyond the Standard Model. Here, we have measured frequency shifts of the ${^1}S_0 \rightarrow {^3}P_1$ and ${^1}S_0 \rightarrow {^3}P_0$ transitions between all stable isotopes of strontium relative to ${^{88}}$Sr. This includes the first reported measurements of the ${^1}S_0 \rightarrow {^3}P_0$ isotope shift of ${^{88}}$Sr-${^{86}}$Sr and ${^{88}}$Sr-${^{84}}$Sr. Using the isotope shift measurements of the two transitions, a King plot analysis is performed. These results, combined with other recent isotope shift measurements in other atomic systems, will help refine atomic structure calculations and theoretical predictions for new physics.

physics.atom-ph↗

arXiv2019

Efficient Arbitrary Simultaneously Entangling Gates on a trapped-ion quantum computer

Efficiently entangling pairs of qubits is essential to fully harness the power of quantum computing. Here, we devise an exact protocol that simultaneously entangles arbitrary pairs of qubits on a trapped-ion quantum computer. The protocol requires classical computational resources polynomial in the system size, and very little overhead in the quantum control compared to a single-pair case. We demonstrate an exponential improvement in both classical and quantum resources over the current state of the art. We implement the protocol on a software-defined trapped-ion quantum computer, where we reconfigure the quantum computer architecture on demand. Together with the all-to-all connectivity available in trapped-ion quantum computers, our results establish that trapped ions are a prime candidate for a scalable quantum computing platform with minimal quantum latency.

quant-ph↗

arXiv2019

Ground-state energy estimation of the water molecule on a trapped ion quantum computer

Quantum computing leverages the quantum resources of superposition and entanglement to efficiently solve computational problems considered intractable for classical computers. Examples include calculating molecular and nuclear structure, simulating strongly-interacting electron systems, and modeling aspects of material function. While substantial theoretical advances have been made in mapping these problems to quantum algorithms, there remains a large gap between the resource requirements for solving such problems and the capabilities of currently available quantum hardware. Bridging this gap will require a co-design approach, where the expression of algorithms is developed in conjunction with the hardware itself to optimize execution. Here, we describe a scalable co-design framework for solving chemistry problems on a trapped ion quantum computer, and apply it to compute the ground-state energy of the water molecule. The robust operation of the trapped ion quantum computer yields energy estimates with errors approaching the chemical accuracy, which is the target threshold necessary for predicting the rates of chemical reaction dynamics.

quant-ph↗