Volume
LIPIcs, Volume 310
19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)
Event
TQC 2024, September 9-13, 2024, Okinawa, JapanEditors
Publication Details
- published at: 2024-08-26
- Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
- ISBN: 978-3-95977-328-7
- DBLP: db/conf/tqc/tqc2024
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Complete Volume
LIPIcs, Volume 310, TQC 2024, Complete Volume
Abstract
LIPIcs, Volume 310, TQC 2024, Complete Volume
Cite as
19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 1-260, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@Proceedings{magniez_et_al:LIPIcs.TQC.2024,
title = {{LIPIcs, Volume 310, TQC 2024, Complete Volume}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {1--260},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024},
URN = {urn:nbn:de:0030-drops-206697},
doi = {10.4230/LIPIcs.TQC.2024},
annote = {Keywords: LIPIcs, Volume 310, TQC 2024, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization
Abstract
Front Matter, Table of Contents, Preface, Conference Organization
Cite as
19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 0:i-0:xvi, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{magniez_et_al:LIPIcs.TQC.2024.0,
author = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
title = {{Front Matter, Table of Contents, Preface, Conference Organization}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {0:i--0:xvi},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.0},
URN = {urn:nbn:de:0030-drops-206700},
doi = {10.4230/LIPIcs.TQC.2024.0},
annote = {Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Multi-qubit Lattice Surgery Scheduling
Abstract
Fault-tolerant quantum computation using two-dimensional topological quantum error correcting codes can benefit from multi-qubit long-range operations. By using simple commutation rules, a quantum circuit can be transpiled into a sequence of solely non-Clifford multi-qubit gates. Prior work on fault-tolerant compilation avoids optimal scheduling of such gates since they reduce the parallelizability of the circuit. We observe that the reduced parallelization potential is outweighed by the significant reduction in the number of gates. We therefore devise a method for scheduling multi-qubit lattice surgery using an earliest-available-first policy, solving the associated forest packing problem using a representation of the multi-qubit gates as Steiner trees. Our extensive testing on random and various Hamiltonian simulation circuits demonstrates the method’s scalability and performance. We show that the transpilation significantly reduces the circuit length on the set of circuits tested, and that the resulting circuit of multi-qubit gates has a further reduction in the expected circuit execution time compared to serial execution.
Cite as
Allyson Silva, Xiangyi Zhang, Zak Webb, Mia Kramer, Chan-Woo Yang, Xiao Liu, Jessica Lemieux, Ka-Wai Chen, Artur Scherer, and Pooya Ronagh. Multi-qubit Lattice Surgery Scheduling. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 1:1-1:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{silva_et_al:LIPIcs.TQC.2024.1,
author = {Silva, Allyson and Zhang, Xiangyi and Webb, Zak and Kramer, Mia and Yang, Chan-Woo and Liu, Xiao and Lemieux, Jessica and Chen, Ka-Wai and Scherer, Artur and Ronagh, Pooya},
title = {{Multi-qubit Lattice Surgery Scheduling}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {1:1--1:22},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.1},
URN = {urn:nbn:de:0030-drops-206712},
doi = {10.4230/LIPIcs.TQC.2024.1},
annote = {Keywords: Scheduling, Large-Scale Optimization, Surface Code, Quantum Compilation, Circuit Optimization}
}
Document
Stochastic Error Cancellation in Analog Quantum Simulation
Abstract
Analog quantum simulation is a promising path towards solving classically intractable problems in many-body physics on near-term quantum devices. However, the presence of noise limits the size of the system and the length of time that can be simulated. In our work, we consider an error model in which the actual Hamiltonian of the simulator differs from the target Hamiltonian we want to simulate by small local perturbations, which are assumed to be random and unbiased. We analyze the error accumulated in observables in this setting and show that, due to stochastic error cancellation, with high probability the error scales as the square root of the number of qubits instead of linearly. We explore the concentration phenomenon of this error as well as its implications for local observables in the thermodynamic limit. Moreover, we show that stochastic error cancellation also manifests in the fidelity between the target state at the end of time-evolution and the actual state we obtain in the presence of noise. This indicates that, to reach a certain fidelity, more noise can be tolerated than implied by the worst-case bound if the noise comes from many statistically independent sources.
Cite as
Yiyi Cai, Yu Tong, and John Preskill. Stochastic Error Cancellation in Analog Quantum Simulation. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 2:1-2:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{cai_et_al:LIPIcs.TQC.2024.2,
author = {Cai, Yiyi and Tong, Yu and Preskill, John},
title = {{Stochastic Error Cancellation in Analog Quantum Simulation}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {2:1--2:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.2},
URN = {urn:nbn:de:0030-drops-206720},
doi = {10.4230/LIPIcs.TQC.2024.2},
annote = {Keywords: Analog quantum simulation, error cancellation, concentration of measure}
}
Document
Efficient Optimal Control of Open Quantum Systems
Abstract
The optimal control problem for open quantum systems can be formulated as a time-dependent Lindbladian that is parameterized by a number of time-dependent control variables. Given an observable and an initial state, the goal is to tune the control variables so that the expected value of some observable with respect to the final state is maximized. In this paper, we present algorithms for solving this optimal control problem efficiently, i.e., having a poly-logarithmic dependency on the system dimension, which is exponentially faster than best-known classical algorithms. Our algorithms are hybrid, consisting of both quantum and classical components. The quantum procedure simulates time-dependent Lindblad evolution that drives the initial state to the final state, and it also provides access to the gradients of the objective function via quantum gradient estimation. The classical procedure uses the gradient information to update the control variables.
At the technical level, we provide the first (to the best of our knowledge) simulation algorithm for time-dependent Lindbladians with an 𝓁₁-norm dependence. As an alternative, we also present a simulation algorithm in the interaction picture to improve the algorithm for the cases where the time-independent component of a Lindbladian dominates the time-dependent part. On the classical side, we heavily adapt the state-of-the-art classical optimization analysis to interface with the quantum part of our algorithms. Both the quantum simulation techniques and the classical optimization analyses might be of independent interest.
Cite as
Wenhao He, Tongyang Li, Xiantao Li, Zecheng Li, Chunhao Wang, and Ke Wang. Efficient Optimal Control of Open Quantum Systems. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 3:1-3:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{he_et_al:LIPIcs.TQC.2024.3,
author = {He, Wenhao and Li, Tongyang and Li, Xiantao and Li, Zecheng and Wang, Chunhao and Wang, Ke},
title = {{Efficient Optimal Control of Open Quantum Systems}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {3:1--3:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.3},
URN = {urn:nbn:de:0030-drops-206733},
doi = {10.4230/LIPIcs.TQC.2024.3},
annote = {Keywords: Quantum algorithm, quantum optimal control, Lindbladian simulation, accelerated gradient descent}
}
Document
One-Wayness in Quantum Cryptography
Abstract
The existence of one-way functions is one of the most fundamental assumptions in classical cryptography. In the quantum world, on the other hand, there are evidences that some cryptographic primitives can exist even if one-way functions do not exist [Kretschmer, TQC 2021; Morimae and Yamakawa, CRYPTO 2022; Ananth, Qian, and Yuen, CRYPTO 2022]. We therefore have the following important open problem in quantum cryptography: What is the most fundamental assumption in quantum cryptography? In this direction, [Brakerski, Canetti, and Qian, ITCS 2023] recently defined a notion called EFI pairs, which are pairs of efficiently generatable states that are statistically distinguishable but computationally indistinguishable, and showed its equivalence with some cryptographic primitives including commitments, oblivious transfer, and general multi-party computations. However, their work focuses on decision-type primitives and does not cover search-type primitives like quantum money and digital signatures. In this paper, we study properties of one-way state generators (OWSGs), which are a quantum analogue of one-way functions proposed by Morimae and Yamakawa. We first revisit the definition of OWSGs and generalize it by allowing mixed output states. Then we show the following results.
1) We define a weaker version of OWSGs, which we call weak OWSGs, and show that they are equivalent to OWSGs. It is a quantum analogue of the amplification theorem for classical weak one-way functions.
2) (Bounded-time-secure) quantum digital signatures with quantum public keys are equivalent to OWSGs.
3) Private-key quantum money schemes (with pure money states) imply OWSGs.
4) Quantum pseudo one-time pad schemes imply both OWSGs and EFI pairs. For EFI pairs, single-copy security suffices.
5) We introduce an incomparable variant of OWSGs, which we call secretly-verifiable and statistically-invertible OWSGs, and show that they are equivalent to EFI pairs.
Cite as
Tomoyuki Morimae and Takashi Yamakawa. One-Wayness in Quantum Cryptography. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 4:1-4:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{morimae_et_al:LIPIcs.TQC.2024.4,
author = {Morimae, Tomoyuki and Yamakawa, Takashi},
title = {{One-Wayness in Quantum Cryptography}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {4:1--4:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.4},
URN = {urn:nbn:de:0030-drops-206744},
doi = {10.4230/LIPIcs.TQC.2024.4},
annote = {Keywords: Quantum Cryptography}
}
Document
Revocable Quantum Digital Signatures
Abstract
We study digital signatures with revocation capabilities and show two results. First, we define and construct digital signatures with revocable signing keys from the LWE assumption. In this primitive, the signing key is a quantum state which enables a user to sign many messages and yet, the quantum key is also revocable, i.e., it can be collapsed into a classical certificate which can later be verified. Once the key is successfully revoked, we require that the initial recipient of the key loses the ability to sign. We construct digital signatures with revocable signing keys from a newly introduced primitive which we call two-tier one-shot signatures, which may be of independent interest. This is a variant of one-shot signatures, where the verification of a signature for the message "0" is done publicly, whereas the verification for the message "1" is done in private. We give a construction of two-tier one-shot signatures from the LWE assumption. As a complementary result, we also construct digital signatures with quantum revocation from group actions, where the quantum signing key is simply "returned" and then verified as part of revocation.
Second, we define and construct digital signatures with revocable signatures from OWFs. In this primitive, the signer can produce quantum signatures which can later be revoked. Here, the security property requires that, once revocation is successful, the initial recipient of the signature loses the ability to find accepting inputs to the signature verification algorithm. We construct this primitive using a newly introduced two-tier variant of tokenized signatures. For the construction, we show a new lemma which we call the adaptive hardcore bit property for OWFs, which may enable further applications.
Cite as
Tomoyuki Morimae, Alexander Poremba, and Takashi Yamakawa. Revocable Quantum Digital Signatures. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 5:1-5:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{morimae_et_al:LIPIcs.TQC.2024.5,
author = {Morimae, Tomoyuki and Poremba, Alexander and Yamakawa, Takashi},
title = {{Revocable Quantum Digital Signatures}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {5:1--5:24},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.5},
URN = {urn:nbn:de:0030-drops-206757},
doi = {10.4230/LIPIcs.TQC.2024.5},
annote = {Keywords: Quantum cryptography, digital signatures, revocable cryptography}
}
Document
The Quantum Decoding Problem
Abstract
One of the founding results of lattice based cryptography is a quantum reduction from the Short Integer Solution (SIS) problem to the Learning with Errors (LWE) problem introduced by Regev. It has recently been pointed out by Chen, Liu and Zhandry [Chen et al., 2022] that this reduction can be made more powerful by replacing the LWE problem with a quantum equivalent, where the errors are given in quantum superposition. In parallel, Regev’s reduction has recently been adapted in the context of code-based cryptography by Debris, Remaud and Tillich [Debris-Alazard et al., 2023], who showed a reduction between the Short Codeword Problem and the Decoding Problem (the DRT reduction). This motivates the study of the Quantum Decoding Problem (QDP), which is the Decoding Problem but with errors in quantum superposition and see how it behaves in the DRT reduction.
The purpose of this paper is to introduce and to lay a firm foundation for QDP. We first show QDP is likely to be easier than classical decoding, by proving that it can be solved in quantum polynomial time in a large regime of noise whereas no non-exponential quantum algorithm is known for the classical decoding problem. Then, we show that QDP can even be solved (albeit not necessarily efficiently) beyond the information theoretic Shannon limit for classical decoding. We give precisely the largest noise level where we can solve QDP giving in a sense the information theoretic limit for this new problem. Finally, we study how QDP can be used in the DRT reduction. First, we show that our algorithms can be properly used in the DRT reduction showing that our quantum algorithms for QDP beyond Shannon capacity can be used to find minimal weight codewords in a random code. On the negative side, we show that the DRT reduction cannot be, in all generality, a reduction between finding small codewords and QDP by exhibiting quantum algorithms for QDP where this reduction entirely fails. Our proof techniques include the use of specific quantum measurements, such as q-ary unambiguous state discrimination and pretty good measurements as well as strong concentration bounds on weight distribution of random shifted dual codes, which we relate using quantum Fourier analysis.
Cite as
André Chailloux and Jean-Pierre Tillich. The Quantum Decoding Problem. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 6:1-6:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{chailloux_et_al:LIPIcs.TQC.2024.6,
author = {Chailloux, Andr\'{e} and Tillich, Jean-Pierre},
title = {{The Quantum Decoding Problem}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {6:1--6:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.6},
URN = {urn:nbn:de:0030-drops-206767},
doi = {10.4230/LIPIcs.TQC.2024.6},
annote = {Keywords: quantum information theory, code-based cryptography, quantum algorithms}
}
Document
Eigenpath Traversal by Poisson-Distributed Phase Randomisation
Abstract
We present a framework for quantum computation, similar to Adiabatic Quantum Computation (AQC), that is based on the quantum Zeno effect. By performing randomised dephasing operations at intervals determined by a Poisson process, we are able to track the eigenspace associated to a particular eigenvalue.
We derive a simple differential equation for the fidelity, leading to general theorems bounding the time complexity of a whole class of algorithms. We also use eigenstate filtering to optimise the scaling of the complexity in the error tolerance ε.
In many cases the bounds given by our general theorems are optimal, giving a time complexity of O(1/Δ_m) with Δ_m the minimum of the gap. This allows us to prove optimal results using very general features of problems, minimising the problem-specific insight necessary.
As two applications of our framework, we obtain optimal scaling for the Grover problem (i.e. O(√N) where N is the database size) and the Quantum Linear System Problem (i.e. O(κlog(1/ε)) where κ is the condition number and ε the error tolerance) by direct applications of our theorems.
Cite as
Joseph Cunningham and Jérémie Roland. Eigenpath Traversal by Poisson-Distributed Phase Randomisation. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 7:1-7:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{cunningham_et_al:LIPIcs.TQC.2024.7,
author = {Cunningham, Joseph and Roland, J\'{e}r\'{e}mie},
title = {{Eigenpath Traversal by Poisson-Distributed Phase Randomisation}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {7:1--7:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.7},
URN = {urn:nbn:de:0030-drops-206779},
doi = {10.4230/LIPIcs.TQC.2024.7},
annote = {Keywords: Randomisation method, Non-unitary adiabatic theorems, Grover problem, Quantum linear systems problem}
}
Document
(Quantum) Complexity of Testing Signed Graph Clusterability
Abstract
This study examines clusterability testing for a signed graph in the bounded-degree model. Our contributions are two-fold. First, we provide a quantum algorithm with query complexity Õ(N^{1/3}) for testing clusterability, which yields a polynomial speedup over the best classical clusterability tester known [Adriaens and Apers, 2023]. Second, we prove an Ω̃(√N) classical query lower bound for testing clusterability, which nearly matches the upper bound from [Adriaens and Apers, 2023]. This settles the classical query complexity of clusterability testing, and it shows that our quantum algorithm has an advantage over any classical algorithm.
Cite as
Kuo-Chin Chen, Simon Apers, and Min-Hsiu Hsieh. (Quantum) Complexity of Testing Signed Graph Clusterability. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 8:1-8:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{chen_et_al:LIPIcs.TQC.2024.8,
author = {Chen, Kuo-Chin and Apers, Simon and Hsieh, Min-Hsiu},
title = {{(Quantum) Complexity of Testing Signed Graph Clusterability}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {8:1--8:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.8},
URN = {urn:nbn:de:0030-drops-206786},
doi = {10.4230/LIPIcs.TQC.2024.8},
annote = {Keywords: Quantum Algorithm, classical Query lower Bound, Graph Property testing}
}
Document
Quantum Non-Identical Mean Estimation: Efficient Algorithms and Fundamental Limits
Abstract
We systematically investigate quantum algorithms and lower bounds for mean estimation given query access to non-identically distributed samples. On the one hand, we give quantum mean estimators with quadratic quantum speed-up given samples from different bounded or sub-Gaussian random variables. On the other hand, we prove that, in general, it is impossible for any quantum algorithm to achieve quadratic speed-up over the number of classical samples needed to estimate the mean μ, where the samples come from different random variables with mean close to μ. Technically, our quantum algorithms reduce bounded and sub-Gaussian random variables to the Bernoulli case, and use an uncomputation trick to overcome the challenge that direct amplitude estimation does not work with non-identical query access. Our quantum query lower bounds are established by simulating non-identical oracles by parallel oracles, and also by an adversarial method with non-identical oracles. Both results pave the way for proving quantum query lower bounds with non-identical oracles in general, which may be of independent interest.
Cite as
Jiachen Hu, Tongyang Li, Xinzhao Wang, Yecheng Xue, Chenyi Zhang, and Han Zhong. Quantum Non-Identical Mean Estimation: Efficient Algorithms and Fundamental Limits. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 9:1-9:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{hu_et_al:LIPIcs.TQC.2024.9,
author = {Hu, Jiachen and Li, Tongyang and Wang, Xinzhao and Xue, Yecheng and Zhang, Chenyi and Zhong, Han},
title = {{Quantum Non-Identical Mean Estimation: Efficient Algorithms and Fundamental Limits}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {9:1--9:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.9},
URN = {urn:nbn:de:0030-drops-206791},
doi = {10.4230/LIPIcs.TQC.2024.9},
annote = {Keywords: Quantum algorithms, Mean estimation, Non-identical samples, Query complexity}
}
Document
Guidable Local Hamiltonian Problems with Implications to Heuristic Ansatz State Preparation and the Quantum PCP Conjecture
Abstract
We study "Merlinized" versions of the recently defined Guided Local Hamiltonian problem, which we call "Guidable Local Hamiltonian" problems. Unlike their guided counterparts, these problems do not have a guiding state provided as a part of the input, but merely come with the promise that one exists. We consider in particular two classes of guiding states: those that can be prepared efficiently by a quantum circuit; and those belonging to a class of quantum states we call classically evaluatable, for which it is possible to efficiently compute expectation values of local observables classically. We show that guidable local Hamiltonian problems for both classes of guiding states are QCMA-complete in the inverse-polynomial precision setting, but lie within NP (or NqP) in the constant precision regime when the guiding state is classically evaluatable.
Our completeness results show that, from a complexity-theoretic perspective, classical Ansätze selected by classical heuristics are just as powerful as quantum Ansätze prepared by quantum heuristics, as long as one has access to quantum phase estimation. In relation to the quantum PCP conjecture, we (i) define a complexity class capturing quantum-classical probabilistically checkable proof systems and show that it is contained in BQP^NP[1] for constant proof queries; (ii) give a no-go result on "dequantizing" the known quantum reduction which maps a QPCP-verification circuit to a local Hamiltonian with constant promise gap; (iii) give several no-go results for the existence of quantum gap amplification procedures that preserve certain ground state properties; and (iv) propose two conjectures that can be viewed as stronger versions of the NLTS theorem. Finally, we show that many of our results can be directly modified to obtain similar results for the class MA.
Cite as
Jordi Weggemans, Marten Folkertsma, and Chris Cade. Guidable Local Hamiltonian Problems with Implications to Heuristic Ansatz State Preparation and the Quantum PCP Conjecture. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 10:1-10:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{weggemans_et_al:LIPIcs.TQC.2024.10,
author = {Weggemans, Jordi and Folkertsma, Marten and Cade, Chris},
title = {{Guidable Local Hamiltonian Problems with Implications to Heuristic Ansatz State Preparation and the Quantum PCP Conjecture}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {10:1--10:24},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.10},
URN = {urn:nbn:de:0030-drops-206804},
doi = {10.4230/LIPIcs.TQC.2024.10},
annote = {Keywords: Quantum complexity theory, local Hamiltonian problem, quantum state ansatzes, QCMA, quantum PCP conjecture}
}
Document
A Direct Reduction from the Polynomial to the Adversary Method
Abstract
The polynomial and the adversary methods are the two main tools for proving lower bounds on query complexity of quantum algorithms. Both methods have found a large number of applications, some problems more suitable for one method, some for the other.
It is known though that the adversary method, in its general negative-weighted version, is tight for bounded-error quantum algorithms, whereas the polynomial method is not. By the tightness of the former, for any polynomial lower bound, there ought to exist a corresponding adversary lower bound. However, direct reduction was not known.
In this paper, we give a simple and direct reduction from the polynomial method (in the form of a dual polynomial) to the adversary method. This shows that any lower bound in the form of a dual polynomial is actually an adversary lower bound of a specific form.
Cite as
Aleksandrs Belovs. A Direct Reduction from the Polynomial to the Adversary Method. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 11:1-11:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{belovs:LIPIcs.TQC.2024.11,
author = {Belovs, Aleksandrs},
title = {{A Direct Reduction from the Polynomial to the Adversary Method}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {11:1--11:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.11},
URN = {urn:nbn:de:0030-drops-206814},
doi = {10.4230/LIPIcs.TQC.2024.11},
annote = {Keywords: Polynomials, Quantum Adversary Bound}
}
Document
Quantum Delegation with an Off-The-Shelf Device
Abstract
Given that reliable cloud quantum computers are becoming closer to reality, the concept of delegation of quantum computations and its verifiability is of central interest. Many models have been proposed, each with specific strengths and weaknesses. Here, we put forth a new model where the client trusts only its classical processing, makes no computational assumptions, and interacts with a quantum server in a single round. In addition, during a set-up phase, the client specifies the size n of the computation and receives an untrusted, off-the-shelf (OTS) quantum device that is used to report the outcome of a single measurement.
We show how to delegate polynomial-time quantum computations in the OTS model. This also yields an interactive proof system for all of QMA, which, furthermore, we show can be accomplished in statistical zero-knowledge. This provides the first relativistic (one-round), two-prover zero-knowledge proof system for QMA.
As a proof approach, we provide a new self-test for n EPR pairs using only constant-sized Pauli measurements, and show how it provides a new avenue for the use of simulatable codes for local Hamiltonian verification. Along the way, we also provide an enhanced version of a well-known stability result due to Gowers and Hatami and show how it completes a common argument used in self-testing.
Cite as
Anne Broadbent, Arthur Mehta, and Yuming Zhao. Quantum Delegation with an Off-The-Shelf Device. In 19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 310, pp. 12:1-12:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)
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@InProceedings{broadbent_et_al:LIPIcs.TQC.2024.12,
author = {Broadbent, Anne and Mehta, Arthur and Zhao, Yuming},
title = {{Quantum Delegation with an Off-The-Shelf Device}},
booktitle = {19th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2024)},
pages = {12:1--12:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-328-7},
ISSN = {1868-8969},
year = {2024},
volume = {310},
editor = {Magniez, Fr\'{e}d\'{e}ric and Grilo, Alex Bredariol},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2024.12},
URN = {urn:nbn:de:0030-drops-206824},
doi = {10.4230/LIPIcs.TQC.2024.12},
annote = {Keywords: Delegated quantum computation, zero-knowledge proofs, device-independence}
}