Optimal Layout Synthesis for Quantum Computing

Tan, Bochen; Cong, Jason

doi:10.48550/arxiv.2007.15671

Cited by 4 publications

(6 citation statements)

References 30 publications

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“…This upgrades the third qubit to |2 or |3 by availing the higher dimensional Hilbert space as temporary storage if and only if the second qubit was |2 or |3 . Finally, a conditional CNOT C +1 Xc is applied to the target qubit q 3 and the third qubit as control as describes in Equation 16. This gate will be executed only when the third qubit were |2 or |3 , as expected and as discussed earlier, it would happen only when the first qubit was |1 state.…”

Section: (B) a Conditional Increment Gate As C +2mentioning

confidence: 99%

“…A logic circuit design using only one qubit gates and two qubit gates does not suffice to be implemented physically. For this reason, there is the qubit mapping or qubit placement algorithm [14][15][16] based on qubit topology, which makes the implementation on physical quantum devices a reality. The operation involving two qubit gates are of most concern rather than single qubit gates while mapping them on physical devices, as the qubit topology may not support the placement of the required two physical qubits adjacently.…”

Section: Introductionmentioning

confidence: 99%

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Moving Quantum States without SWAP via Intermediate Higher Dimensional Qudits

Saha¹,

Saha²,

Chakrabarti³

2021

Preprint

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Quantum algorithms can be realized in the form of a quantum circuit. To map quantum circuit for specific quantum algorithm to quantum hardware, qubit mapping is an imperative technique based on the qubit topology. Due to the neighbourhood constraint of qubit topology, the implementation of quantum algorithm rightly, is essential for moving information around in a quantum computer. Swapping of qubits using SWAP gate moves the quantum state between two qubits and solves the neighbourhood constraint of qubit topology. Though, one needs to decompose the SWAP gate into three CNOT gates to implement SWAP gate efficiently, but unwillingly quantum cost with respect to gate count and depth increases. In this paper, a new formalism of moving quantum states without using SWAP operation is introduced for the first time to the best of our knowledge. Moving quantum states through qubits have been attained with the adoption of temporary intermediate qudit states. This introduction of intermediate qudit states has exhibited a three times reduction in quantum cost with respect to gate count and approximately two times reduction in respect to circuit depth compared to the state-of-the-art approach of SWAP gate insertion. Further, the proposed approach is generalized to any dimensional quantum system.

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Section: (B) a Conditional Increment Gate As C +2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Moving Quantum States without SWAP via Intermediate Higher Dimensional Qudits

Saha¹,

Saha²,

Chakrabarti³

2021

Preprint

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“…Qubit assignment [15][16][17][18][19] (often referred to as qubit routing, qubit allocation, or quantum compilation) has been extensively studied as a tool for improving the performance of circuits executed on hardware. Qubit assignment typically includes modifying logical circuits to run on hardware when the gateset and connectivity constraints of the device do not match those of the logical program, typically with the goal of minimizing the number of additional operations introduced to the program.…”

Section: A Prior Workmentioning

confidence: 99%

Qubit assignment using time reversal

Peters,

Shyamsundar,

et al. 2022

Preprint

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As the number of qubits available on noisy quantum computers grows, it will become necessary to efficiently select a subset of physical qubits to use in a quantum computation. For any given quantum program and device there are many ways to assign physical qubits for execution of the program, and assignments will differ in performance due to the variability in quality across qubits and entangling operations on a single device. Evaluating the performance of each assignment using fidelity estimation introduces significant experimental overhead and will be infeasible for many applications, while relying on standard device benchmarks provides incomplete information about the performance of any specific program. Furthermore, the number of possible assignments grows combinatorially in the number of qubits on the device and in the program, motivating the use of heuristic optimization techniques. We approach this problem using simulated annealing with a cost function based on the Loschmidt Echo, a diagnostic that measures the reversibility of a quantum process. We provide theoretical justification for this choice of cost function by demonstrating that the optimal qubit assignment coincides with the optimal qubit assignment based on state fidelity in the weak error limit, and we provide experimental justification using diagnostics performed on Google's superconducting qubit devices. We then establish the performance of simulated annealing for qubit assignment using classical simulations of noisy devices as well as optimization experiments performed on a quantum processor. Our results demonstrate that the use of Loschmidt Echoes and simulated annealing provides a scalable and flexible approach to optimizing qubit assignment on near-term hardware.

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“…Finally, scheduling operations to minimize total execution time [16,25]. In general, the compilation problem is computationally hard and while some attempts at optimal solutions have been pursued [33,36,40] the dominant approach is heuristics.…”

Section: The Compilation Problemmentioning

confidence: 99%

Orchestrated trios: compiling for efficient communication in Quantum programs with 3-Qubit gates

Duckering

Baker

Litteken

et al. 2021

Proceedings of the 26th ACM International Conference on Architectural Support for Programming Languages and Operating Systems

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Current quantum computers are especially error prone and require high levels of optimization to reduce operation counts and maximize the probability the compiled program will succeed. These computers only support operations decomposed into one-and two-qubit gates and only two-qubit gates between physically connected pairs of qubits. Typical compilers first decompose operations, then route data to connected qubits. We propose a new compiler structure, Orchestrated Trios, that first decomposes to the three-qubit Toffoli, routes the inputs of the higher-level Toffoli operations to groups of nearby qubits, then finishes decomposition to hardware-supported gates.This significantly reduces communication overhead by giving the routing pass access to the higher-level structure of the circuit instead of discarding it. A second benefit is the ability to now select an architecture-tuned Toffoli decomposition such as the 8-CNOT Toffoli for the specific hardware qubits now known after the routing pass. We perform real experiments on IBM Johannesburg showing an average 35% decrease in two-qubit gate count and 23% increase in success rate of a single Toffoli over Qiskit. We additionally compile many near-term benchmark algorithms showing an average 344% increase in (or 4.44x) simulated success rate on the Johannesburg architecture and compare with other architecture types. CCS CONCEPTS• Computer systems organization → Quantum computing; • Software and its engineering → Compilers.

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Optimal Layout Synthesis for Quantum Computing

Cited by 4 publications

References 30 publications

Moving Quantum States without SWAP via Intermediate Higher Dimensional Qudits

Moving Quantum States without SWAP via Intermediate Higher Dimensional Qudits

Qubit assignment using time reversal

Orchestrated trios: compiling for efficient communication in Quantum programs with 3-Qubit gates

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