Analytical approach to swift nonleaky entangling gates in superconducting qubits

Economou, Sophia E.; Barnes, Edwin

doi:10.1103/physrevb.91.161405

Cited by 55 publications

(90 citation statements)

References 46 publications

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“…A Hamiltonian similar to the one in Eq. 7 has been addressed in a previous work on superconducting qubits [25], where the SWIPHT (speeding up wave forms by inducing phases to harmful transitions) protocol was introduced and control pulses were designed for the cnot and cz gates. The analytical methods developed in the aforementioned work and earlier works [23,24,27,28] are the basis for the control pulses we present in the following sections.…”

Section: Two-qubit Hamiltonianmentioning

confidence: 99%

“…To achieve shallower circuit depth, it is therefore of interest to be able to directly implement these gates instead of decomposing them in terms of cnots. In previous works [23][24][25], it has been demonstrated that by using a hyperbolic secant (sech) control pulse, Ω(t) = Ω 0 sech(σt) with Ω 0 /σ = integer, a cyclic evolution can be induced, and thus local phase gates are easily implemented. However, the method used in those works involves an auxiliary excited state and, therefore, it is not directly applicable to the current case.…”

Section: Cnot Gate From Partial Reverse-engineeringmentioning

confidence: 99%

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Fast high-fidelity entangling gates for spin qubits in Si double quantum dots

et al. 2019

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Implementing high-fidelity two-qubit gates in single-electron spin qubits in silicon double quantum dots is still a major challenge. In this work, we employ analytical methods to design control pulses that generate high-fidelity entangling gates for quantum computers based on this platform. Using realistic parameters and initially assuming a noise-free environment, we present simple control pulses that generate cnot, cphase, and cz gates with average fidelities greater than 99.99% and gate times as short as 45ns. Moreover, using the local invariants of the system's evolution operator, we show that a simple square pulse generates a cnot gate in less than 27 ns and with a fidelity greater than 99.99%. Last, we use the same analytical methods to generate two-qubit gates locally equivalent to √ cnot and √ cz that are used to implement simple two-piece pulse sequences that produce high-fidelity cnot and cz gates in the presence of low-frequency noise.

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Section: Two-qubit Hamiltonianmentioning

confidence: 99%

Section: Cnot Gate From Partial Reverse-engineeringmentioning

confidence: 99%

Fast high-fidelity entangling gates for spin qubits in Si double quantum dots

et al. 2019

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“…While Ref. 43 demonstrated the efficacy of SWIPHT for a set of typical parameters, a full examination of its regime of validity and its robustness to parameter variations and decoherence and relaxation has yet to be carried out.…”

Section: -41mentioning

confidence: 99%

“…In Ref. [43], it was shown that achieving an identity operation on the harmful transition requires that the following conditions be satisfied:…”

mentioning

confidence: 99%

Robustness of error-suppressing entangling gates in cavity-coupled transmon qubits

2017

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Superconducting transmon qubits comprise one of the most promising platforms for quantum information processing due to their long coherence times and to their scalability into larger qubit networks. However, their weakly anharmonic spectrum leads to spectral crowding in multiqubit systems, making it challenging to implement fast, high-fidelity gates while avoiding leakage errors. To address this challenge, we use a protocol known as SWIPHT [Phys. Rev. B 91, 161405(R) (2015)], which yields smooth, simple microwave pulses designed to suppress leakage without sacrificing gate speed through spectral selectivity. Here, we determine the parameter regimes in which SWIPHT is effective and demonstrate that in these regimes it systematically produces two-qubit gate fidelities for cavity-coupled transmons in the range 99.6%-99.9% with gate times as fast as 23 ns. Our results are obtained from full numerical simulations that include current experimental levels of relaxation and dephasing. These high fidelities persist over a wide range of system parameters that encompass many current experimental setups and are insensitive to small parameter variations and pulse imperfections.

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“…A protocol that avoids leakage in singlequbit gates called DRAG has been introduced [6-10] and experimentally used [11,12]. For two-qubit gates, various approaches have been developed both for microwave drive [3,[13][14][15][16][17][18][19][20][21] and for tuning [22][23][24][25][26][27][28][29]. In general, techniques developed in the context of one-or two-qubit gates are not directly applicable to three-qubit gates.…”

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confidence: 99%

Fast microwave-driven three-qubit gates for cavity-coupled superconducting qubits

et al. 2017

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Although single and two-qubit gates are sufficient for universal quantum computation, single-shot three-qubit gates greatly simplify quantum error correction schemes and algorithms. We design fast, high-fidelity three-qubit entangling gates based on microwave pulses for transmon qubits coupled through a superconducting resonator. We show that when interqubit frequency differences are comparable to single-qubit anharmonicities, errors occur primarily through a single unwanted transition. This feature enables the design of fast three-qubit gates based on simple analytical pulse shapes that are engineered to minimize such errors. We show that a three-qubit ccz gate can be performed in 260 ns with fidelities exceeding 99.38%, or 99.99% with numerical optimization.Quantum information processing is one of the most exciting and rapidly growing fields of modern science, in large part due to quantum algorithms, which promise exponential speedup in solving important problems. Quantum two-level systems (qubits) are the fundamental carriers of quantum information, and among the most promising of these are qubits based on superconducting circuits [1,2]. Such an architecture is attractive because of the mature circuit fabrication technology and the ability to couple qubits together via resonators to implement logic gates [3].For universal quantum computing, a certain set of high-fidelity logic gates suffices to implement any algorithm; this set is comprised of single-qubit gates along with one maximally entangling two-qubit gate. Threequbit gates, which play a prominent role in algorithms, can be decomposed in terms of a sequence of single-and two-qubit gates [4]. In the case of a maximally entangling three-qubit control-control-z (ccz) gate (described below), one must perform seven single-qubit gates and six entangling two-qubit gates, as shown in Fig. 1. The large number of gates needed makes it natural to explore whether a direct, single-shot three-qubit gate is preferable in terms of speed and fidelity.There are two ways to implement logic gates in superconducting qubit systems. One is via tuning of the energy levels, which brings states into and out of resonance. The other is via oscillating microwave fields that induce transitions between energy levels, which offers the advantage of less susceptibility to charge noise. Both approaches face the challenge of spectral crowding in these systems, especially in the context of superconducting transmon qubits where each qubit is a weakly anharmonic oscillator out of which the two lowest levels are selected to encode information [5]. In the case of many qubits coupled together, there is a large number of closely spaced transitions that need to be avoided during quantum gate operations. Generically, a way to avoid unwanted transitions is to consider the time-energy uncertainty principle, which tells us to make the operations slow. In realistic systems, however, this is not an option, as we need to perform operations at a time scale that is much faster than decay and decoherence. ...

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Analytical approach to swift nonleaky entangling gates in superconducting qubits

Cited by 55 publications

References 46 publications

Fast high-fidelity entangling gates for spin qubits in Si double quantum dots

Fast high-fidelity entangling gates for spin qubits in Si double quantum dots

Robustness of error-suppressing entangling gates in cavity-coupled transmon qubits

Fast microwave-driven three-qubit gates for cavity-coupled superconducting qubits

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