Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic near-single-cycle optics at 1 kHz   We present a laser source delivering waveform-controlled 1.5-cycle pulses
that can be focused to relativistic intensity at 1 kHz repetition rate. These
pulses are generated by nonlinear compression of high-temporal-contrast
sub-25\,fs pulses from a kHz Ti:Sapphire double-chirped pulse amplifier in a
stretched flexible hollow fiber compressor scaled for high peak power. The
unique capabilities of this source are demonstrated by observing
carrier-envelope phase effects in laser-wakefield acceleration of relativistic
electrons for the first time.

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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: patt-sol
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci